I have a jailbroken & unlocked iphone 3g running on 3.1.3. It froze yesterday so I had to restore, jailbreak, and unlock it all over again.
I previously had MMS and internet enabled using the modmyi repo "t-mobile us flexpaid/postpaid" found on cydia. I tried to search it again but it's not there.

To make matters worse, my "cellular data network" tab is completely missing so I can't even try to manually input it.

please, please, please help! :]