What could cause two of my receptacles to stop working?
If you are using a simple outlet tester you could get a false positive.  You should always use something that draws some decent current, like a lamp. Here is a related story.  I unplug the electric clothes dry recently while cleaning the ducting. My wife plugged it back in afterward.  From then on, although the drum turned fine, the heat was intermittent. After checking a couple other things, I pushed the plug all the way in. Apparently, the motor ran on 120V, where the heater coil ran on 220V. Needless to say, I checked the plug and outlet for burns.