Cant see wi-fi network

I am running Mountain Lion 10.8.2 on my MacBook Pro, this morning I was connected to the wi-fi network in the office and then suddenly I wasn't. The SSID of the network in question no longer appears in the list of available networks and if I try to manually connect it says no network found. I have restarted several times to no avail. My iPad and iPhone are both connected to the same network with no apparent issues. There are multiple PCs also connected to this network. What's going on?

The first step is to power down your router. Count to 10 then reconnect it.

Thanks, have given that a try but still can't see the network. I left it off for a full minute and restarted, same problem!

Can you connect by Ethernet and have it work ok?

Are you able to connect to or detect other wireless networks?