|That happened to me last week and what I did was open my router's configuration utility in a web browser and changed the wireless channel. The best channels are 1, 6 or 11.|
Mine was set to "Automatic" so I changed that to "Manual" then selected my preferred channel.
You will need to use a PC or laptop which is connected by ethernet cable to the router to change it's wireless channel, don't try to do it with a wireless connection.
I changed the channel and when I returned to my laptop and refreshed the network list, my router's SSID was listed and I could then establish a connection to it.
After changing the wireless channel on your router, all the devices which connect to it will automatically adjust to the new channel.