Wireless Problems

[lde42]

Awhile ago i got the WL-500g and it was working for quite awhile then it stopped working on my Dad's computer (the one that is connected through the lan port). And now it wont work at all. The configuration is my modem (telewest Broadband) is connected to Wan my dad is connected through Lan and my computer should be working through my wireless adapter. I tried moving the modem from Wan to Lan and it worked on my dad's computer but not on mine, even when i got an extra cable and connected mine through lan. I badly need help with this.

Thanks