My Facebook chat is locked for all mobile chat softwares, not only ebuddy, nimbuzz also. When I try to login it says: Session Terminated. Can someone help me?

Try these:
1. Scan your mobile for viruses
2. Delete ebuddy, nimbuzz and install a fresh copy.
3. Maybe the problem is with your network. Make sure it is working.
4. If all the above fails. Maybe your phone needs a software/firmware update. So contact your nearby mobile store.