pick a plug

I can't get a Pick a Plug LED to light up on either of my adapters. They were working perfectly two days ago, but the router and modem were disconnected a day ago and reconnected, and now the adapters can't seem to find each other. 

I've tried setting them up next to each other in the same room, and nothing happens. 

I've turned them both off and then off, and the Pick a Plug light comes on briefly on the adapter connected to the router, but quickly goes off. The Pick a Plug light does not come on at all on the other adapter.

I've done factory resets on both adapters and tried them again, still, no Pick a Plug light comes on.

What else should I be doing? Throwing them out?

Please help !