Keşke söküğü kıyafet takasından önce fark etseydik.

Keşke expresses a wish, usually with a feeling of regret.

In this sentence, it means something like:

• If only ...
• I wish ...
• We wish ... had ...

So keşke tells you that the speaker is unhappy that the thing did not happen.

Because after keşke, Turkish often uses a form that expresses an unreal or regretted past situation.

• fark ettik = we noticed
• fark etseydik = if only we had noticed

So fark etseydik does not just report a past event. It shows that the event did not happen, and the speaker wishes it had.

It breaks down like this:

• fark et- = to notice
• -se = conditional/wish-type marker
• -ydi = past element
• -k = we

So:

fark et-se-ydi-k
= if only we had noticed

This is a very common structure after keşke for past regrets.

Because Turkish usually does not need subject pronouns when the verb already shows the person.

Here, the ending -k in etseydik tells you the subject is we.

So Turkish does not need biz unless the speaker wants extra emphasis.

• Keşke fark etseydik. = If only we had noticed.
• Biz keşke fark etseydik. = If only we had noticed with extra emphasis on we

It can be either, depending on context.

As an adjective, sökük can mean something like:

• ripped
• coming apart at the seam
• unstitched

But in this sentence, it is being used as a noun:

• sökük = the tear / the ripped part / the loose seam

This is common in Turkish: a word that can describe something can also be used as a noun when the context makes it clear.

Because it is the specific direct object of the verb fark etmek.

Turkish often marks a definite/specific direct object with the accusative ending.

• sökük = a tear / tear
• söküğü = the tear / the ripped part as a specific object

Also, the final k changes to ğ before a vowel-ending suffix:

• sökük
• sökük + ü
• söküğü

So the -ü is the accusative ending, and the spelling change is normal Turkish consonant softening.

Because önce normally follows a noun phrase in the ablative case.

The pattern is:

• X-den önce = before X
• X-den sonra = after X

So:

• kıyafet takasından önce = before the clothing swap

This is a very common Turkish structure.

Because kıyafet takası is a noun compound.

In Turkish, expressions like clothing swap are often built like this:

• kıyafet = clothing
• takas = exchange / swap
• kıyafet takası = clothing swap

That -ı on takası is part of the compound structure.

Then, because önce needs the ablative, you add -ndan:

• kıyafet takası
• kıyafet takası + ndan
• kıyafet takasından

The n is a buffer consonant that appears after that possessive-type ending.

It is written as two words:

• fark etmek

This is a very common Turkish verb type: a noun plus etmek.

Other examples:

• yardım etmek = to help
• kabul etmek = to accept
• hareket etmek = to move, act

Even though it is written as two words, it functions as a single verbal idea.

Yes. Turkish word order is flexible, although the verb usually stays at the end.

This sentence puts focus naturally on söküğü and leads into the regret at the end.

You could also hear variations such as:

• Keşke kıyafet takasından önce söküğü fark etseydik.

That version may sound slightly more neutral to some speakers, because the time phrase comes earlier.
The original sentence is still completely natural.

The important thing is that ğ is not pronounced like a hard English g.

In söküğü, the ğ usually softens or lengthens the surrounding vowel rather than making a strong consonant sound.

A rough guide:

• sö → like a rounded vowel, similar to German ö
• kü
• ğü → the ğ is very soft; think of it as stretching the vowel a bit

So it sounds roughly like:

• sö-küü
• or in careful pronunciation, sö-kü-ü

The exact sound can vary a little, but the key point is: do not say a hard g.

A helpful way to see it is:

• Keşke
  • regretted wish
• [specific object]
• [time phrase]
• [verb at the end]

So here:

• Keşke = if only
• söküğü = the tear / ripped part
• kıyafet takasından önce = before the clothing swap
• fark etseydik = we had noticed

This is a very typical Turkish sentence shape: the verb comes last, and other parts appear before it in the order the speaker wants to present them.