That would be kahvaltıydım

I was breakfast is "kahvaltıydım", kahvaltı ettim (if you check your dictionay for etmek) is to do breakfast.

So Gümüş was right, I was wrong (stupid mistake now I think about it - thank you Gümüs) - and I stıll remember what you told me thıs mornıng about kahvaltı ettim.

Are you sure about that? Can you show us some resources?

 I dont think that is correct. I have some grammarbooks that are used at turkish universities, and they state otherwise. Furthermore, if you debate that it is not ebil as a suffix but bilmek as the verb being used to describe ´ability´, then consequently ´not being able to´, should also be ´bilmemek´, which is not the case.

Gidebilirim.

Gidebilmem. which is not the case, it is Gidemem.

Gidebilir miyim? Gidemezsin, then should be:

Gidebilir miyim? Gidebilmezsin.

I stand to see ebil-abil as suffixes that are added inside a verb, but for learners it can be easy (and logic) to think of it as just adding the verb bilmek after the verb stam+e/a. But I dont think that is grammatically a correct way of approaching it. Anyway, it is just a matter of ´technicalities´

Is there a difference between kahvaltı yapmak and kahvaltı etmek? The last one surely only means for one to have breakfast, but can the first also mean to prepare breakfast, as in kahvaltıyı hazırlamak?

For exmaple:

Uyan, kalk! Kahvaltıyı hazırladım! - Wake up, get up! I prepared breakfast!

Could you also say:

Uyan, kalk! Ben sana kahvaltı yaptım

Or would that be wrong? I just wondered after reading these, because personally I say ´kahvaltıyı hazırladım´ and ´kahvaltı ettim´, I dont use yapmak really...

A Turkish friend told  me to use kahvaltı yapmak for both preparıng breakfast and havıng/eating breakfast.  But then people use different expressions all the time - I suppose there are many ways of saying this, just as they are in English and I would imagine in Dutch too!

I don´t think that is the point. "Gidebilmem" sounds like Azeri Turkish accent;

yapabilmirem > yapamıyorum/yapamam

That may be right as origins but I have never read/heard it.

In my opinion:

to have a breakfast: kahvaltı yapmak or [kahvaltı etmek (from TDK Dictionary)]

to prepare a breakfast: kahvaltı hazırlamak

*I prepared a breakfast for you.

*sana kahvaltı yaptım is incorrect but "sana kahvaltı hazırladım" is correct.

 Thanks Seyit - maybe I misunderstood - it was because I said ´kahvaltı yedim´ and he said this was wrong and it should be ´yaptım´ but I always thought ´kahvaltı yapmak´ was ´to make breakfast´.  Now I know better but I think I will just put the plate in front of my husband and say ´Buyurun!´  - much simpler!!

 I already corrected as -ebilmek and -abilmek. 

Now please check below from the site http://www.edebiyatogretmeni.net/fiiller.htm

It is called Yeterlilik Fiili, because it is a verb..

1) Yeterlilik Fiili ( fiil + ebil-) :

Cümleye gücü yetme ve olasýlýk anlamý katar.Fiilin üzerine ebilmek getirilerek oluþturulur.

* Okula geç kalýrsam öðretmenim kýzabilir. (o)

* Bu genç yaþýmda ölebilirim (o)

*En güzel þiirlerimi söylemeden gidebilirim buralardan (o)

* Bir gece ansýzýn gelebilirim. (o)

* Sevinçten kapýnda bayýlabilirim.

* Sýnýfý geçebilirim (g.y)

UYARI: Yeterlilik fiilinin olumsuzunda bil- fiili düþer. Fiilin üzerine –ama , -eme getirilerek yapýlýr.

* Yapabilirim à yapamam. (yeterlilik birleþik fiilinin olumsuzu)

* yaparým    à   yapmam  ( geniþ zamanýn olumsuzu)  

* Görebilirsin à göremezsin (yeterlilik birleþik fiilinin olumsuzu)

* Atamam kendimi mavi denize dünya güzel. (atabilirim: yeterlilik birleþik fiilinin olumsuzu)