Solve my problem sir

Question

hi, i am himanshu from bahadurgarh. i have a samsung sgh X650 mobile phone. i love my phone so much but a major problem occurs in my phone that it is not able to search for the signal and always shows no sevice available or call not allowed even after the insertion of simcard.i have showed my phone to number of mechanics but they didn"t get success to solve my problem .all other functions of phone works after we insert simcard. but it is not able to search signal.please sir, help me to solve my problem. i cannot replace my phone due to moneyproblem. also i am not able to get internat settings in my phone. i have bsnl connection.ihad also restart problem iwent to service centre 3 or more times to solve my problem they dont solve this problem piz sir solve this problem......