Restore speakers to default settings

My computer has sound coming out of only one speaker, and it sounds as if its in a cave (very echoy).
I believe the problem stems from a program I had that allowed me a change my sound effects and the change from mono to stereo.
My problem now is that I can no longer find this program. It used to start up when I put In a new audio device. What I want to do is simply change all My effects back to default but I don't know if I need to find the program.

It's hard to understand how software that's been removed could be changing the sound. Go to Control Panel/Add Remove Programs. If the program is still on the machine, it should appear in the list. If it's in the list, you lost the link, not the software. Locate the software in Program Files, right click on it and select "Create Shortcut" then drag the new shortcut out on the desktop.

If the software is not on the list, I'd look for a hardware problem in the sound system.