Problem with Qtek 8100

[Guest Pikstar]

The problem is, that my volume +/- button on the left of my Qtek doesn´t work. It worked perfectly yesterday. My phone rings, but when i´m going to watch a video etc. on the phone, there is no sound at all. Could the problem be that i´ve deleted a file, and if i have, which one then ? Hope you can help me with this problem.