Two days ago, there was a brief power outage. It wasn't until tonight that I realized that all recorded shows were erased from my DVR. How can they be restored?
Unlikely to have been erased. Can you make new recordings? if not your hard drive may not be working properly. Certainly try the tools to fix your STB.
Under DVR Configuration menu, there is an option for recently deleted.
You could check there.
I think there is another opton for DVR actions or something like that.
But as previously stated, there is a chance that your HD is going bad.