Can't turn the volume up or down

The problem first starts when i try turning the 19 inch astar tv on. if a small box that says astar doesn't show up and it is instead the whole screen that says astar, then i get a blue screen. but if the small box shows up, the tv works fine....except the volume. this is the 2nd time this has happened and i do not know what i did to fix it the first time. pretty much, you cant use the volume buttons on the remote or the tv to control the volume. what you have to do is set the volume to whatever level you want it, turn the tv off then back on and it will be set at the volume you turned it off on. what do i do to fix both of these problems?