I think my wife messed up the sound on our RCA HD40-300 when messing with the menu it wasworking before she messed with it how do I return the sound

Open the menu and go in the Sound setting . In there open the submenus and put them this way
- Sound settings: Left&Right Balance should be set to middle; in Left&Right speakers to Internal; If your exact model came with an integrated Subwoofer set it to Internal;
- Sound type to Stereo;
- Sound mode to Normal;
- Surround effect - don't touch
- SAP - untick/disable;
- Automatic sound level - preferably disabled;
- Headphones - don't touch;
- Graphic equalizer - set to Standard in Sound Preset
That is all.