Do texts from an iphone 4s go into a deleted or trash file when deleted?
They're gone forever. Into space.
On the phone yes...BUT all texts end up in your phone providers "super computer". Each company keeps them for a certain amount of time. Usually from a week to a year.
Deleted text messages on an iPhone are gone for good. If you have an iTune account, you can recover them. iTunes usually sync the files in your phone like photos, text messages and contacts into your iTunes account.