"bence siirim unuttun zaten. ama neyse, tuncayin telefon numaralarin var mi?"

is it terrible?

I don´t think so. My attempt is. (modified 2008.8.14 don´t know how I missed "unut´.

"According to me my poem you must forget anyway but what if, what is your Tunca´s telephone number? "

Possibly also "what is your night phone number?"

 According to me I´ve forgotten my  poem already,do you have Tunac´s telephone number?

I think you´ve forgotten my poem already, but anyway, do you have Tuncay´s phone number?

 If this is what you want to say:

I think you already forgot my poem but anyway do you have Tuncay´s phone number?

Bence şiirimi çoktan unuttun ama neyse, sende Tuncay´ın telefon numarası var mı?