The volume on technics SL-BD22 turntable will not turn up and stays at one volume

Since the turntable itself doesn't have a volume control the problem is with the amp it is connected to. It should be connected to an amp with a dedicated phono socket. It's no use connecting it to a tape or aux or CD socket. These sockets do not have a built in pre-amp for the magnetic cartridge. If your amp doesn't have a dedicated phono socket then you can buy a Magnetic Cartridge Pre-amp that will plug into a tape socket etc on the amp and have the deck plugged into it. If plugged into a none dedicated socket though you can hear it, the volume will be very low compared to other sources. If you have got it plugged into a dedicated phono socket and the volume is still low, then the internal built pre-amp inside your amp for the deck has failed and will need to be repaired. The pre-amp failure will not effect any other functions of the amp.