Thomson router won't work wirelessly but will with the cable?

My Thomson router has suddenly stopped working wirelessly, it works with the internet when I plug the cable into my laptop however I cannot connect anything wirelessly to it. Sometimes it doesn't show up in the list of available wifi connections but when it does it brings up the message Unable to connect. The wireless light on the router is green. I have tried everything, resetting the router and resetting back to factory settings.. What can I do to fix it?