Samsung galaxy s3 for att, touchwiz home has stopped working

following links are the user manual for your phone
http://www.att.com/support_static_files/manuals/Samsung_Galaxy_S_III.pdf Samsung Galaxy III Manual User Guide

go into the touchwiz app and clear the cache. it might help to restart your phone every now and then.

Go to playstore and download a new keyboard then in setting change default in language and settings to the keyboard

Your Samsung Galaxy S3 must be restricted to some specific network. That is why it allows only emergency calls when a SIM card from some other network is inserted in. You need to unlock your Samsung Galaxy S3 to make it work with all SIM cards. You can unlock your Samsung Galaxy S3 safer and easier using unlock code. You can get the accurate unlock code for a Samsung Galaxy S3 from Unlock-Zone.com at affordable cost. Good luck.

-<()>--<()>--<()>--<()>--<()>--<()>--<()>-
..............UNLOCKING INSTRUCTIONS..............
-<()>--<()>--<()>--<()>--<()>--<()>--<()>-

Method 1:
1 - Switch ON your Samsung Galaxy S3 with a NOT ACCEPTED SIM Card.
2 - Samsung Galaxy S3 will ask for "Password".
3 - Enter the Unlock Code.

OR (if the Samsung Galaxy S3 shows "Insert Correct SIM Card")

Method 2:
1 - Switch ON your Samsung Galaxy S3 with a NOT ACCEPTED SIM Card.
2 - Don't bother about what's being displayed on your Samsung Galaxy S3.
3 - Compose : #0111*CODE#.

SOURCE: MobileUnlockGuide.com

Does it come up at all? Have you tried to factory reset it?

Pls how do i unlock samsung GT18320