Ég finn ekki lyklakortið mitt, þess vegna kemst ég ekki inn.

Finn is the 1st person singular present tense form of the verb að finna (to find).

So:

• að finna = to find
• ég finn = I find / I am finding

Icelandic verbs change form depending on the subject, so you cannot usually use the infinitive finna where English would use find.

A few present-tense forms of finna are:

• ég finn = I find
• þú finnur = you find
• hann/hún/það finnur = he/she/it finds
• við finnum = we find

So Ég finn ekki... means I do not find... or more naturally I can’t find...

In Icelandic, ekki is the normal word for not, and it usually comes after the finite verb.

So:

• Ég finn ekki... = I do not find...
• literally: I find not...

This is very common in Icelandic:

• Ég skil ekki. = I do not understand.
• Hún kemur ekki. = She is not coming.
• Við sjáum ekki bílinn. = We do not see the car.

So the placement of ekki here is completely normal.

Lyklakortið is the definite form of lyklakort.

Breakdown:

• lykill = key
• kort = card
• lyklakort = key card / access card
• lyklakortið = the key card

Icelandic often forms compound nouns like this, just like English does.

The ending -ið is the definite article attached to the noun. Icelandic usually adds the to the end of the word instead of using a separate word.

So:

• lyklakort = a key card
• lyklakortið = the key card

Because lyklakort is a neuter noun, and the possessive my must agree with the noun in gender, number, and case.

The basic possessive forms are:

• minn = my (masculine)
• mín = my (feminine)
• mitt = my (neuter)

Since lyklakort is neuter, you use mitt:

• lyklakortið mitt = my key card

Compare:

• bíllinn minn = my car (bíll is masculine)
• taskan mín = my bag (taska is feminine)
• húsið mitt = my house (hús is neuter)

It is the direct object of finn, so it is in the accusative case.

In this sentence:

• Ég = subject
• finn = verb
• lyklakortið mitt = direct object

So the noun phrase is accusative.

However, with this particular noun, the form looks the same as nominative:

• nominative: lyklakortið
• accusative: lyklakortið

And the possessive mitt also looks the same here.

So even though the case is accusative, there is no visible change in this phrase.

Þess vegna means because of that, for that reason, or therefore.

It links the second clause to the first one:

• Ég finn ekki lyklakortið mitt = I can’t find my key card
• þess vegna kemst ég ekki inn = therefore / because of that, I can’t get in

It is a very common expression in Icelandic.

Literally, it comes from:

• þess = of that
• vegna = because of / due to

But learners usually treat þess vegna as a fixed phrase meaning therefore / that’s why.

This is because Icelandic follows a verb-second rule in main clauses.

That means the finite verb usually comes in the second position of the clause.

In the first clause:

• Ég finn ekki...
• subject first, verb second

In the second clause, þess vegna comes first. Because that first position is already taken, the verb must come next:

• þess vegna kemst ég ekki inn

So the order is:

1. þess vegna
2. kemst
3. ég
4. ekki
5. inn

This is a very important Icelandic word-order pattern.

Compare:

• Ég kemst ekki inn.
• Í dag kemst ég ekki inn. = Today I can’t get in.
• Þess vegna kemst ég ekki inn. = Therefore I can’t get in.

Kemst is a form of the verb að komast.

Að komast often means things like:

• to get
• to get through
• to reach
• to manage to get somewhere
• to be able to get in/out/up/down, depending on context

In this sentence:

• kemst ég ekki inn = I can’t get in

The form kemst is the 1st/3rd person singular present tense form:

• ég kemst = I get / I can get / I manage to get
• hann kemst = he gets / he can get

This verb is very common in everyday Icelandic.

Because Icelandic often expresses that idea through the main verb itself, especially with komast.

So:

• Ég kemst ekki inn literally looks like I do-not-get-in
• but idiomatically it means I can’t get in / I’m unable to get in

English often uses can, but Icelandic does not always need a separate modal verb where English does.

Another possible Icelandic structure would use geta (can, be able to), but komast ekki inn is very natural here and is probably the most idiomatic choice.

Inn means in or inside, but here it is a directional adverb, meaning movement into somewhere.

So:

• vera inni = to be inside
• fara inn = to go in
• komast inn = to get in / gain entry

In this sentence:

• kemst ég ekki inn = I can’t get in

So inn completes the idea of entering a place.

Yes. Icelandic uses compound nouns very heavily, just like German and often like English.

Here:

• lykill
  • kort → lyklakort

Notice that the first part changes form slightly:

• lykill becomes lykla- in the compound

This kind of linking is very normal in Icelandic compounds.

Other examples:

• bók
  • hill a → bókahilla = bookshelf
• sjónvarp
  • stöð → sjónvarpsstöð = TV station

So lyklakort is a good example of a very typical Icelandic word-building pattern.

Yes, that is possible, but it changes the emphasis.

• lyklakortið mitt is the most neutral and natural way to say my key card
• mitt lyklakort puts more emphasis on my

So:

• Ég finn ekki lyklakortið mitt. = I can’t find my key card.

  • neutral, everyday wording

• Ég finn ekki mitt lyklakort. = I can’t find my key card.

  • more contrastive, like my key card as opposed to someone else’s

In most ordinary situations, lyklakortið mitt is the better choice.

The comma separates two main clauses:

• Ég finn ekki lyklakortið mitt
• þess vegna kemst ég ekki inn

In Icelandic, commas are often used between clauses like this, especially when one clause explains the consequence of the other.

So the comma helps show the structure:

• first: the problem
• second: the result

It is similar to English punctuation in sentences like:

• I can’t find my key card, so I can’t get in.

Yes. Very often, present tense + ekki gives the natural meaning can’t find in context.

So:

• Ég finn ekki lyklakortið mitt
  can mean
• I don’t find my key card literally, but
• I can’t find my key card naturally

English usually prefers can’t find here, and Icelandic often just uses finn ekki.

This is one of those places where a very literal word-for-word translation can sound less natural than the real meaning.