Dosyanın yedeklemesini yapsaydım, yanlış dizine kaydedince bu kadar panik olmazdım.

Because Turkish is linking file with backup in a genitive-possessive structure.

• dosyanın = of the file
• yedeklemesi = its backup / the backup of it

So dosyanın yedeklemesi literally means something like the file’s backup or the backing up of the file.

This is the same pattern as:

• arabanın kapısı = the car’s door
• evin çatısı = the house’s roof

So dosyanın is there because the backup belongs to or is associated with the file.

It has several layers:

• yedekle- = to back up
• -me = verbal noun suffix, making yedekleme = backing up / backup
• -si = 3rd person possessive, so yedeklemesi = its backup
• -ni = accusative case, because this whole thing is the definite object of yapmak

So:

• yedeklemesini yapmak = literally to do/make its backup
• in natural English: to make a backup of it / to back it up

This kind of stacking is very normal in Turkish.

Both are possible.

A simpler version would be:

• Dosyayı yedekleseydim... = If I had backed up the file...

The version with yedeklemesini yapmak is a noun-based expression, and Turkish often uses this kind of structure:

• araştırma yapmak = to do research
• temizlik yapmak = to do cleaning

So yedeklemesini yapmak is not wrong at all; it just sounds a bit more expanded than the simpler verb yedeklemek.

Yapsaydım is a past counterfactual conditional form. It means if I had done/made.

Breakdown:

• yap- = do, make
• -sa = conditional if
• -ydı = past
• -m = I

So:

• yapsaydım = if I had done

This form is used for unreal past situations, especially things the speaker did not actually do.

Because kaydetmek uses the destination in the dative case.

You save something to somewhere:

• dosyayı masaüstüne kaydetmek = to save the file to the desktop
• dosyayı yanlış dizine kaydetmek = to save the file to the wrong directory

So:

• yanlış dizine = to the wrong directory

The -e / -a ending is the dative here.

Kaydedince means when I saved it, once I saved it, or upon saving it.

It comes from:

• kaydet- = save
• -ince = a converb ending meaning when / once / after

So:

• kaydedince = when saving / when I saved

This -ince form is very common in Turkish for time relations:

• eve gelince = when I come/came home
• bitirince = when/after finishing

In this sentence, it sets the situation that triggered the panic.

The subject is understood to be the same person as in the rest of the sentence: I.

So kaydedince is understood as:

• ben kaydedince = when I saved

The object is also omitted because it is obvious from context: it is the file.

So the full idea is something like:

• onu yanlış dizine kaydedince = when I saved it to the wrong directory

Turkish very often leaves out subjects and objects when they are already clear.

Turkish often expresses states and reactions with a noun or adjective plus olmak.

• panik olmak = to panic / to be in a panic

So:

• panik olmazdım = I wouldn’t have panicked

This may feel strange to an English speaker, because English prefers a simple verb. But in Turkish, panik olmak is very natural.

You may also hear:

• panik yapmazdım

That is also common in speech, but panik olmak and panik yapmak are not exactly identical in tone. Panik olmak is a straightforward state/reaction.

Because Turkish usually expresses this kind of unreal past result with -mazdı / -mezdi or similar past conditional-result forms.

So the pattern is often:

• ... yapsaydım, ... olmazdım
• ... olsaydı, ... gelmezdim
• ... bilseydim, ... söylemezdim

Here:

• olmazdım = I would not have been / I would not have become
• in natural English: I wouldn’t have panicked

By contrast, olmayacaktım usually means something closer to I was not going to be or I wouldn’t be going to be, so it is not the normal choice here.

Bu kadar means this much or so much.

So:

• bu kadar panik olmazdım = I wouldn’t have panicked this much / so much

It intensifies the degree of panic.

Turkish often uses bu kadar before adjectives, adverbs, or similar predicate words:

• bu kadar yorgun = this tired
• bu kadar hızlı = this fast
• bu kadar üzgün = this sad

Here it tells you the speaker is talking about the level of panic, not just panic in general.

In this sentence, kaydedince itself does not carry counterfactual marking. It simply means when saving / when I saved.

The counterfactual part is mainly in:

• Dosyanın yedeklemesini yapsaydım = If I had backed up the file
• ... panik olmazdım = ... I wouldn’t have panicked

So the sentence suggests that saving it to the wrong directory is the event the speaker is reacting to, and the speaker is imagining how that reaction would have been different if a backup had existed.

In other words, it sounds like:

• the mistaken saving happened
• the backup did not happen
• the speaker is imagining a different reaction under that unreal condition

Yes, it is natural.

Turkish often puts:

1. the condition first
2. then any time-setting or circumstance
3. then the main result at the end

So this sentence is organized as:

• Dosyanın yedeklemesini yapsaydım = if I had backed up the file
• yanlış dizine kaydedince = when I saved it to the wrong directory
• bu kadar panik olmazdım = I wouldn’t have panicked this much

That is a very Turkish way to package the information.

Yes. A very natural simpler version would be:

• Dosyayı yedekleseydim, yanlış dizine kaydedince bu kadar panik olmazdım.

This avoids the heavier yedeklemesini yapmak structure and uses the direct verb yedeklemek.

Also, depending on the context, some speakers might prefer:

• yanlış klasöre instead of yanlış dizine

if they mean an ordinary folder rather than a more technical directory.

So the original sentence is understandable and grammatical, but there are slightly simpler everyday alternatives.