If the Mac is not even detecting your router's wireless and in case the router's been reset by a power surge or other outside factor, have a look at the literature which came with the router (or download the manual from Netgear) for how to address the router's setup screens. Once in check that wireless access point is enabled.
Also try turning off wireless security temporarily until you re-establish a reliable wireless link.
If the Mac is detecting your router's wireless, you might think about interference.
See if you can detect neighbouring wifi networks and switch to a channel 5 stops from the strongest.
NB: when sorting out my friends' Mac wireless problems, I've always used a PC, so my guidance may not be so helpful if your don't have access to one.