Ok, you're on the right track. The fact that all of the receivers are out means its either the power inserter (The SWM Box) or the cabling... so here's what you need to do.. I'm gonna list in steps
1. I'm guessing that like most people, you use a power strip to plug everything in. If that's true, try unplugging the SWM box from the power strip and plugging it into the wall (Leave it unplugged for at least one full minute before plugging back in). If that's not possible, run an extension cord from another outlet for test purposes. Once you have it plugged back in, reset the receiver and see if it works. If it does, the power strip is the problem and you'll need to figure out a way to get the SWM box plugged directly into the wall (Because of how power strips work, a new one probably wont fix the problem).
2. Check the cabling.. I know you said you didnt touch anything, but just double check, and do it this way...
IF the coax coming from the wall is connected to a wall plate, disconnect it and reconnect it (DONT use a wrench.. Just Finger tight.. this goes for all connections)
follow that cable to the SWM Box. It should be connected to the one marked "Out to SWM", disconnect/reconnect it.
The other cable on the SWM box ("Out to IRD").. Disconnect/Reconnect it
follow that cable... it "probably" goes up to the receiver.. make sure it's connected (finger tight) to the one marked "Satellite In 1/SWM".
For what its worth... it's that cable between the wall and the SWM box thats probably causing the problem... if you do these steps and still no go, then the only other option you'd have would be to try replacing that one cable, if you can. You'll want an RG6 type coax cable. There's a couple different kinds in the stores, get the cheap one (Oh, and if you have some coax laying around somewhere, any kind will work for a test to make sure that's it).
It's possible the cable got pinched and or bent too sharply when you were swapping out the TV's or something.