If only two speakers are not working and all the rest are, it seems that perhaps the terminal connections need to be soldered back together on the inside of the receiver. That's a typical cause when only 1 or 2 speakers go out. If all the speakers were out I'd say it's something more serious internally. But, just one or two speakers sounds like a connection came loose inside. If the warranty is out, take the top off and take a peek. It's usually a pretty easy fix if the connections are the problem.
If you are only using 5.1 speakers, did you have the wires removed from the back of the receiver (for whatever reason) and accidentally connect them to the "Rear" (which are used only in 7.1 systems) instead of "Surround" channels?
Did the surround speakers get turned off in the receiver's setup menus?
A forum community dedicated to home theater owners and enthusiasts. Come join the discussion about home audio/video, TVs, projectors, screens, receivers, speakers, projects, DIY’s, product reviews, accessories, classifieds, and more!