Als ich gestern müde war, likte ich automatisch alles Mögliche, ohne mich zu konzentrieren.

Als ich gestern müde war is a subordinate clause. In German subordinate clauses introduced by words like als, weil, dass, wenn, the conjugated verb goes to the end.

So:

• Main clause: Ich war gestern müde. (verb in second position)
• Subordinate clause: … als ich gestern müde war. (verb war at the end)

In your sentence, that whole subordinate clause comes first:

• Als ich gestern müde war, (subordinate clause, verb at the end)
• likte ich automatisch … (main clause, verb in second position)

In the past, German distinguishes:

• als = one specific time or episode in the past

  • Als ich gestern müde war, …
    One particular situation yesterday.

• wenn = whenever, repeatedly, or in general

  • Wenn ich müde war, likte ich immer alles Mögliche.
    Whenever I was tired (repeated habit).

Here, you are talking about a specific occasion yesterday, so als is the correct choice.

In a main clause, word order is typically:

1. First position: some element (subject, time phrase, etc.)
2. Second position: finite verb
3. Then the rest

Example:

• Ich war müde.

But in a subordinate clause like als ich gestern müde war, the finite verb goes to the end of the clause. Everything else (subject, time, adjectives) goes before it:

• als (subordinating conjunction)
• ich (subject)
• gestern (time)
• müde (predicate adjective)
• war (finite verb at the end)

The comma is required because you are closing a subordinate clause and then starting a main clause:

• Subordinate clause: Als ich gestern müde war,
• Main clause: likte ich automatisch alles Mögliche, …

In a main clause in German, the finite verb must be in second position. When you start the sentence with a subordinate clause, that whole clause counts as position 1. The finite verb of the main clause then must come next, in position 2:

1. Als ich gestern müde war, (whole block = position 1)
2. likte (finite verb, position 2)
3. ich automatisch alles Mögliche, ohne mich zu konzentrieren.

So likte ich is correct here. You could also say:

• Ich likte automatisch alles Mögliche, als ich gestern müde war.

Here Ich is position 1 and likte is position 2.

Yes, liken is a widely used colloquial verb in modern German meaning to like something on social media.

It behaves like a regular weak verb:

• Infinitive: liken
• Present:
  • ich like
  • du likst
  • er/sie/es likt
  • wir liken
  • ihr likt
  • sie/Sie liken
• Simple past:
  • ich likte
  • du liktest
  • er/sie/es likte
  • wir likten …

However, many speakers prefer the perfect tense in everyday speech:

• Ich habe (alles Mögliche) gelikt.

Both ich likte (simple past) and ich habe gelikt (present perfect) are understandable, but in spoken German, habe gelikt sounds more natural in many regions.

Yes:

• liken (and likte) is informal and very modern, used especially about social media.
• In more neutral or formal German you might say:
  • Ich habe automatisch alles Mögliche positiv bewertet.
  • Ich habe automatisch alles Mögliche angeklickt.

For everyday conversation about social media, liken / gelikt / likte is very usual and natural, especially among younger speakers.

Alles Mögliche literally means something like all (kinds of) possible things, but idiomatically it means:

• all sorts of things
• all kinds of stuff

Grammatically:

• möglich is an adjective (possible).
• When you turn an adjective into a noun-like word (nominalization), German capitalizes it.
• So das Mögliche = the possible (thing).
• In your sentence, Mögliche is nominalized and therefore capitalized.

Alles here works like a determiner meaning everything / all, and Mögliche is the nominalized adjective that completes the phrase:

• Ich likte automatisch alles Mögliche …
  = I automatically liked all sorts of things …

Grammatically, alles Mögliche is treated as singular neuter, because alles refers to everything as a whole and nominalized adjectives like das Mögliche are neuter singular.

However, conceptually it refers to many different things – so in meaning it is like a plural (all sorts of things), even though its grammatical form is singular.

You can compare:

• alles Gute – all the best (as a whole)
• alles Französische – everything French

In your sentence:

• Ich likte automatisch alles Mögliche …

Alles Mögliche is the direct object of likte, so it is in the accusative case.

Pattern:

• Nominative: alles Mögliche (e.g. Alles Mögliche interessiert mich.)
• Accusative: alles Mögliche (e.g. Ich likte alles Mögliche.)

For neuter singular with alles, nominative and accusative look the same, so you see no visible case change here.

After ohne followed by a verb, German usually uses a zu-infinitive construction:

• ohne zu schlafen – without sleeping
• ohne zu essen – without eating
• ohne mich zu konzentrieren – without concentrating (myself)

Structure:

• ohne
  • [optional object or pronoun] + zu
    • infinitive

The zu is required in this pattern. So:

• Correct: ohne mich zu konzentrieren
• Incorrect: ohne mich konzentrieren (sounds wrong)

This ohne … zu + infinitive corresponds roughly to English without + -ing:

The verb sich konzentrieren is reflexive in German in the meaning to concentrate (one’s attention). You normally say:

• Ich konzentriere mich.
• Du konzentrierst dich.
• Er konzentriert sich.

So, when you use the infinitive konzentrieren in the ohne … zu construction, you keep the reflexive pronoun:

• ohne mich zu konzentrieren – without concentrating
• ohne dich zu konzentrieren – without concentrating
• ohne sich zu konzentrieren – without concentrating

Ohne zu konzentrieren is grammatically possible but feels incomplete or unusual here, because konzentrieren is normally used reflexively in this sense. Native speakers will almost always use sich (in the right form).

Reflexive pronouns in German take:

• Accusative when there is no other direct object
• Dative when there is another direct object in accusative

Examples:

1. No other direct object:

   • Ich konzentriere mich.
     (mich is reflexive, accusative)

2. With an additional direct object:

   • Ich kämme mir die Haare.
     die Haare = direct object (accusative)
     mir = reflexive, dative

In Ich likte automatisch alles Mögliche, ohne mich zu konzentrieren, the reflexive pronoun refers to the subject ich and is the only object of konzentrieren, so it must be mich (accusative), not mir.

In zu-infinitive clauses, the zu normally comes directly before the infinitive verb, and any objects or pronouns come before zu:

• mich zu konzentrieren
• das Buch zu lesen
• ihn anzurufen (for separable verbs, zu goes in the middle: an
  • zu
    • rufen → anzurufen)

So the normal pattern is:

• [preposition] + [object/pronoun] + zu
  • [infinitive]

That is why:

• ohne mich zu konzentrieren is correct.
• ohne zu mich konzentrieren is wrong word order.

Both are possible:

• Simple past: Ich likte automatisch alles Mögliche …
• Present perfect: Ich habe automatisch alles Mögliche gelikt …

In spoken German, especially in southern and western regions, people strongly prefer the present perfect for past actions:

• Ich habe alles Mögliche gelikt.

In written German, especially narrative texts (stories, novels), the simple past is very common:

• Ich likte alles Mögliche.

So your sentence with likte sounds more like written narrative style. In everyday speech, habe gelikt would be more natural for many speakers.

You could, but it is unusual and stylistically odd.

With verbs like sein (to be) and haben (to have), German strongly prefers the simple past for most contexts:

• Als ich gestern müde war, … (sounds completely normal)
• Als ich gestern müde gewesen bin, … (possible, but marked / unusual)

The form with gewesen bin may appear in some dialects or for special emphasis, but the standard, natural form here is clearly:

• Als ich gestern müde war, likte ich automatisch alles Mögliche, ohne mich zu konzentrieren.