Only right speaker working for both playback and recording!

As I put in the title, whenever I try to record or monitor any audio in Reaper (v4.22) I can only hear the right side of the feed. It says that both sides are coming through, but I only hear the right side. I have tried using different headphones and speakers, but the problem persists. I know it's probably something really simple, but this issue is absolutely KILLING me. Any and all help is very welcome! Specs HP Pavilion dv7 Windows 7 Reaper v4.22 M-Audio Fast Track C400 M-Audio AV 40's

Welcome to the forum! It's usually this: the input and output selection in Options->Preferences->Audio->Device is a range selection, meaning the first and last in/outputs of a range have to be selected. Did you enable all available outputs? Can you otherwise post a screenshot of your Preferences -> Audio Device page?

Works like a charm! Thanks for the help.