Can't change the time on

this might have happened due to some virus attack in to your handset ...

due to this virus attack some of the firmware files which are needed to operate that task has got corrupted ...

so try giving the restore factory settings ....

if problem persists then just try using this EEPROM master reset code ....

*2767*2878# Custom reset

*2767*3855# eeprom reset...

doing this will delete everything in the phone memory including contacts stored in phone memory ...