[Problem N900] Cannot recieve & send sms, Also shows SIM not recognised. But I can make Call & Receive call. Help required !!!!!!!

Able to latch to the network & also Network name appears in the screen. Able to scan through the available network .

Recent incident happened: More number of sms`s are sent to this number , suddenly SIM not recognised symbol appeared.
Restarted the mobile multiple times. Also tried settings -> Restore original settings. no use..

Pls guide me to make my mobile function normal. THANK YOU !!!

Maemo 5, VERSION: 20.2010.36-2.004