"unknown error has occurred" while updating or downloading any app from app store

If I am trying to UPDATE or DOWNLOAD any app from app store I get a message at "An unknown error has occurred" this is not allowing me download or update anything from app store!!!

and I even checked my software update of ipod touch and the recent itunes but still I dont have any result!!!

I even reset my ipod!!!

Please help me!!!

shall i restore my ipod once?