Re: volume buttons not working on motorola 1020
Who replaced the battery?
If the service center replaced it, take it back to them immediately and report the issue.
If you (or anyone else other than the authorized service center), you could try checking if some dirt is getting in the way of the contacts of the button controls. If that doesn't work, you will still need to take the phone to a service center to have it checked and repaired.
I'm not sure what a "Motorola 1020" is, though.