Power Check: As silly as it sounds, make sure the receiver is plugged in and turned on.
Volume Check: Make sure you have the volume control turned up enough. If you don't hear anything, though, be sure to turn it back down so you won't get thrown across the room when you do find the cause.
Speaker Selection: make sure the proper set of speakers (A or B) is selected.
Mute Control: Check to be sure the receiver isn't muted.