Toplantı odasındaki dağınıklık yüzünden dosyaları bulmak zor oldu.

Because toplantı odası is a noun compound meaning meeting room.

• toplantı = meeting
• oda = room
• toplantı odası = meeting room

In Turkish noun compounds, the second noun usually takes a 3rd person possessive ending:

• oda → odası

Then, to say the one in / the one at, Turkish adds:

• -da / -de = in, at
• -ki = the one that is in/at...

So:

• toplantı odası = meeting room
• toplantı odasında = in the meeting room
• toplantı odasındaki = the one in the meeting room / the ... in the meeting room

Here it modifies dağınıklık, so the phrase means:

• toplantı odasındaki dağınıklık = the mess in the meeting room

Here -ki turns a location phrase into something that can describe a noun, similar to an English relative phrase like that is in or in the.

For example:

• odada = in the room
• odadaki masa = the table in the room
• literally: the in-the-room table

So in your sentence:

• toplantı odasındaki dağınıklık
• literally: the mess that is in the meeting room

It is very common in Turkish to use -ki this way instead of a longer relative clause.

That -n- is a buffer consonant used when certain suffixes are added after possessive endings.

The structure is roughly:

• oda = room
• odası = its room / room of the meeting → part of the compound toplantı odası
• odasında = in its room / in the meeting room
• odasındaki = the one in its room / in the meeting room

That -n- helps connect the endings smoothly. You will often see this after possessed forms:

• evi → evinde
• araba? not possessed → arabada
• arabası → arabasında

So odasındaki is normal and expected.

Dağınıklık means mess, clutter, untidiness, or disorder, depending on context.

It comes from:

• dağınık = messy, scattered, untidy
• -lık / -lik / -luk / -lük = a suffix that can make an abstract noun

So:

• dağınık = messy
• dağınıklık = messiness / clutter / disorder

In this sentence, dağınıklık is best understood as the clutter or the mess.

Yüzünden usually means because of, often with a negative feeling or result.

So:

• dağınıklık yüzünden = because of the clutter / due to the mess

This fits well because the result is a problem: finding the files was difficult.

By contrast:

• için can mean for or because of, but it is more neutral
• sebebiyle also means because of / due to, and sounds more formal

Examples:

• Yağmur yüzünden geç kaldım. = I was late because of the rain.
• Senin için geldim. = I came for you.
• Yoğun trafik sebebiyle gecikme oldu. = There was a delay due to heavy traffic.

So yüzünden is a very natural choice here because the cause is inconvenient.

Because dosyaları is in the accusative case, which usually marks a specific/definite direct object.

• dosya = file
• dosyalar = files
• dosyaları = the files / specific files

So:

• dosya bulmak = to find a file / to do file-finding in a general sense
• dosyaları bulmak = to find the files / to find specific files

The sentence is talking about particular files that someone was trying to find, so the accusative is appropriate.

Yes, dosyaları can be ambiguous in isolation. Depending on context, it can mean:

• the files (plural accusative)
• his/her files
• their file
• their files

But in this sentence, the most natural reading is:

• dosyaları bulmak = to find the files

Why? Because the surrounding structure strongly suggests a direct object in the accusative after bulmak.

Context usually clears this kind of ambiguity up in Turkish.

Because the action to find the files is being treated as a thing/concept, which then becomes the subject of zor oldu.

So the structure is:

• dosyaları bulmak = finding the files / to find the files
• zor oldu = became difficult / was difficult

Together:

• Dosyaları bulmak zor oldu. = Finding the files was difficult.

This is very common in Turkish. The infinitive -mak / -mek often works like an English -ing form or to + verb phrase.

Both are possible, but they are slightly different in feel.

• zordu = it was difficult
• zor oldu = it became difficult / it turned out to be difficult / it was difficult

In many contexts, zor oldu sounds a bit more natural when talking about how something went in a specific situation. It can suggest the difficulty was experienced as the event happened.

So:

• Dosyaları bulmak zordu. = Finding the files was difficult.
• Dosyaları bulmak zor oldu. = Finding the files turned out to be difficult / was difficult.

The difference is small here, but oldu often gives a more event-based, conversational tone.

The sentence is:

• Toplantı odasındaki dağınıklık yüzünden dosyaları bulmak zor oldu.

A useful breakdown is:

• Toplantı odasındaki dağınıklık yüzünden = because of the mess in the meeting room
• dosyaları bulmak = to find the files
• zor oldu = was difficult / became difficult

So the overall structure is:

[Cause] + [Action as noun/infinitive] + [Result/adjective + verb]

Turkish often places the verb at the end, so this is very normal word order.

Yes, but Turkish does not need a dummy subject like English it.

English says:

• It was difficult to find the files.

Turkish instead uses the infinitive phrase itself as the subject:

• Dosyaları bulmak zor oldu.
• literally: Finding the files became difficult.

So there is no separate word for it here.

Yes:

• Toplantı = meeting
• odası = room-of / room (as part of meeting room)
• odasındaki = the one in the meeting room / in the meeting room
• dağınıklık = mess, clutter
• yüzünden = because of
• dosyaları = the files
• bulmak = to find
• zor = difficult
• oldu = became / was

A more literal full gloss would be:

• Because of the mess in the meeting room, finding the files became difficult.

Yes, several ways are possible. For example:

• Toplantı odasındaki dağınıklık nedeniyle dosyaları bulmak zor oldu.
  More formal; nedeniyle = because of, due to.

• Toplantı odası çok dağınık olduğu için dosyaları bulmak zor oldu.
  Because the meeting room was very messy, it was hard to find the files.

• Toplantı odasındaki karmaşa yüzünden dosyaları bulmak zor oldu.
  Using karmaşa = confusion, chaos, mess.

Your original sentence is natural and idiomatic.