|Can the computer in question see other wireless networks? If it can see others and not yours, the issue is your WLAN. If it can't see any, then the computers wireless interface is the most likely suspect.|
Is the NIC enabled?
Is it working properly?
Check in Device Manager to confirm the above.
If it's enabled and working, check the software you use to search for available wireless networks, is it functioning properly?
Do you have a wireless SOHO Router providing your wireless network? If not, why don't you? For $100.00 or less you could get a good wireless router and make your life, and your home network, a lot easier to deal with.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.