Neyleyim İstanbul´u?

(Without somebody/something) what will i do with/in Istanbul ? 

(Without somebody/something) Who cares Istanbul ?

Thank you, harp00n. Got it.

But I can´t understand what it consists of. It should be ne + ile + y (buffer) + ´I am´ maybe but if so what is motivating the accusative object?

Strange.

I really dont know, how will i explain that, but;

"Neyleyim ?" means "Ne yapayım ?"

For example; 

Sensiz/sen olmadıktan sonra Istanbul´u neyleyim/ne yapayım ?

Parasız/Param olmadıktan sonra tatili neyleyim/ne yapayım ?

You can think about it like a How are you? and what´s up ? Neyleyim coming from daily Turkish, i wish i would help more...

You did help, I think I can use it now. I am just curious because usually Turkish sayings are very transparent but this seems more complex.

Your comparing it to ne yapayım makes me think. Could it be...

Could it be that in neyleyim letter -e- has a double role? It is part of the instrumental -le- but at the same time in a foxy way it is understood as a subjunctive marker, just like it was a verb. And what is more surprising, even a transitive verb.

What a jump from one part of speech to another if I have any clue.

maybe is the verbe eylemek = etmek , it is use rarely used this days

Yes, you said it, ulak. It looks like the perfect explanation. Subjunctive it is.

But still it must be a shortened form, shouldn´t it be ne eyleyeyim?