G530H no network available

i have G530h,which had no network but singal was full when i was trying to make a call they pop up tht no network available,then i update it to lollipop then it,s imei changed after flashing on lollipop,then i return to KK but imei still same not matching with back sticker.how to solve this its still same signal bar is full sim detecting but when try to make a call then pop up no network availabe.Bst team please help me.