why does my soound all the sudden sound quiet and twangy, kind of like it is playing through a headphone speaker at a loud volume?

I have tries everything, going into the MIDI settings doesnt help, my volume is up all the way and every volume setting is to the max. I dont know if my speakers just need to be replaced or if it is a software issue. my sound does work, but it sounds to have about 1/8th the volume and absolutely no bass, just pure treble...please help!!!