2 pc's both only work with cables, wifi not working

I have had a wifi router made by another company for some time but then I got the dreaded "No Internet Connection" message on my #1 machine and as I couldn't immediately sort it, I fired up my second laptop and that too was unable to make a connection. I then used a cable direct from my Wimax modem and everything is fine on BOTH laptops. Ahah ! We said. The router has failed; no apparent reason but perhaps it's the transformer, after all we've got the builders in and the power is going off and on all the time..... every other piece of equipment works perfectly though. So, I bought a new Netgear router and that should be all right. But it isn't. I still have the issue on both routers on both laptops - they work with cables but not with wifi. Anybody got any ideas? A virus somewhere? Well my Avast is paid for and is current and says there are no problems. The Wimax carries not only the Internet connection but also my telephone which works perfectly and the local forum is not posting any problems.