I PHONE

Hello,people,please i neeed yr help

i recently bought an i phone3G 3.0 (3 days ago)!it was unlocked,when i got home ,i tried to put music in the phone using i tunes:initially the phone was working,i could call my friends and sms them,then there was a message on itunes which said "install updates",i clicked on to install,from there my phone only showed that it is connected to itunes, with a padlock and wrote "no service".i can neither call nor sms:other services are okay.it is still writing no service,i donno what to do,plis help me out
by the way i am living in Malaysia,i dont know what to do to make it call.