Nigde ne vidim ključ, a danas moram da idem na posao.

Because Serbian normally uses negative concord: if you use a negative word like nigde (nowhere), the verb is also negated with ne.

So:

• Nigde ne vidim ključ. = I can’t see the key anywhere / I see the key nowhere.

This is different from standard English, where two negatives are usually avoided. In Serbian, this is the normal and correct pattern.

You’ll see the same thing in other examples:

• Niko ne zna. = Nobody knows.
• Nikad ne idem tamo. = I never go there.
• Ništa ne razumem. = I understand nothing.

Nigde means nowhere or, in more natural English, often anywhere in a negative sentence.

So although the literal structure is closer to Nowhere do I see the key, natural English is usually:

• I can’t see the key anywhere.

It comes from the question word gde (where):

• gde = where
• nigde = nowhere

Vidim is the 1st person singular present tense of videti (to see).

So:

• vidim = I see

In the sentence:

• ne vidim = I do not see / I can’t see

Serbian often uses the present tense in situations where English might use either I don’t see or I can’t see, depending on context.

Because ključ is a masculine inanimate noun, and in Serbian, masculine inanimate nouns usually have the same form in the nominative and accusative singular.

Here, ključ is the direct object of vidim, so it is in the accusative:

• nominative: ključ = key
• accusative: vidim ključ = I see the key

Since it’s masculine inanimate, the form stays the same.

Compare with a masculine animate noun:

• vidim čoveka = I see the man

There, the accusative changes.

A is a very common Serbian conjunction. Here it means something like:

• and
• but
• while
• whereas

depending on context.

In this sentence, a links two ideas with a slight contrast:

• Nigde ne vidim ključ, a danas moram da idem na posao.
• I can’t see the key anywhere, and/but I have to go to work today.

It feels a bit like: ...and the problem is that... or ...but the thing is...

So a is softer and more contrastive than a simple i (and).

In modern Serbian, after verbs like morati (must / have to), it is very common to use:

• da + present tense

So:

• moram da idem = I have to go

Literally, that is something like I must that I go, but in Serbian this is completely normal grammar.

You may also encounter an infinitive in some contexts or styles:

• moram ići

But moram da idem is extremely common and natural in everyday Serbian.

Idem is from ići, the basic imperfective verb meaning to go.

Here it fits because the speaker is talking about the necessity of going somewhere:

• moram da idem na posao = I have to go to work

If you used a different motion verb, the meaning could shift:

• otići often emphasizes going away / leaving
• poći can mean set off / start going

So ići / idem is the most neutral and expected choice here.

Because Serbian uses na posao to mean to work / to the workplace in the sense of going there.

So:

• ići na posao = to go to work

This is a fixed, very common expression.

Also, after verbs of motion, na often takes the accusative to show direction:

• na posao = to work

Compare:

• Idem na posao. = I’m going to work.
• Na poslu sam. = I’m at work.

So:

• na posao = motion toward
• na poslu = location

It is accusative singular.

The noun is:

• nominative: posao = job / work

After na with motion, Serbian uses the accusative:

• idem na posao = I’m going to work

This is one of the common preposition + case patterns you’ll need to learn:

• na + accusative for movement toward something
• na + locative for being at/on something

Yes, Serbian word order is fairly flexible, and Ne vidim ključ nigde is possible.

Both are understandable, but the emphasis is slightly different:

• Nigde ne vidim ključ puts stronger focus on nowhere / anywhere
• Ne vidim ključ nigde starts more neutrally with the verb phrase

Serbian often moves words around for emphasis, rhythm, or style. The version you were given is very natural and highlights the frustrating fact that the key is nowhere.

Danas means today.

It adds urgency to the second clause:

• a danas moram da idem na posao
• and today I have to go to work

The speaker is not just saying they need the key in general — they need it today, which makes the situation more pressing.

Moram can cover both must and have to, depending on context.

So:

• Moram da idem na posao. can mean:
• I have to go to work.
• I must go to work.

In everyday English, have to is often the most natural translation. Serbian morati does not always sound as formal or strong as English must can sound.

A rough guide:

• Nigde ≈ NEEG-deh
• ne ≈ neh
• vidim ≈ VEE-deem
• ključ ≈ klyooch
• a ≈ ah
• danas ≈ DAH-nahs
• moram ≈ MOH-rahm
• da ≈ dah
• idem ≈ EE-dehm
• na posao ≈ nah POH-sah-oh

A few useful pronunciation notes:

• č is like ch in church
• lj is a soft sound, roughly like lli in million for many English speakers
• Serbian spelling is quite phonetic, so words are usually pronounced close to how they are written

Yes, it sounds natural.

Nigde ne vidim ključ, a danas moram da idem na posao. is a normal everyday sentence. It sounds like someone is worried because they can’t find their key and they need to leave for work.

A native speaker might also say things like:

• Ne mogu nigde da nađem ključ.
• Nigde ne mogu da pronađem ključ.

But your original sentence is absolutely fine and natural.