Is it possible that your password remains as it was earlier after going to the service center for unlocking I have doubt that my phone has been unlocked by someone from its service center but when I saw my phone and I found the same lock which was earlier so I want to ask that is it possible that people at service center can recover the password after unlocking it?
No it's not like that. It depends like if you are having an hardware problem ,they might wipe out your data and if are having an internal problem then they will wipe your data and then they will go through their procedures.