Please help to me stupid-stupid-stupid!

I dont remember the version of iPhone i had, but i've unlocked it.
I cant really even remember the way ive unlocked it because ive tried many way up until ive managed to unlock/jailbreak it.

I've upgraded my iphone to version 1.1.1 and since then my iphone is LOCKED.

even with an at&t sim it tells my i got an incorrect sim.
Is there any way i can fix that? i dont mind doing anything, downgrading, upgrading, locking, unlocking, whatever it takes to fix the problem!

thanks for anyone that helps!