Backspace and Delete key not working

Hello, my backspace and keyboard button arn't working! I am currently on a Mac OS X 10.7. I am typing this from an old keyboard that I had that had a USB plugged into the mac. Not even when I press shift or fn and backspace/space does it work. Just when I push the button, it doesn't work/register. It worked fine yesterday and was just working 1-2 hours ago, then it derped up. I restarted my computer, it worked fine then when I left for a minute and came back it wasn't working with backspace and space. the keyboard and mouse are wireless. Thanks! Please Please help!