Wireless network is completely invisible

My house mate's laptop (that used to work fine) had suddenly decided not to pick up our wireless network. She is picking up the neighbours network but ours is not appearing at all. My computer nd my mobile phone connects to my network fine Any idea what could be the problem?

"used to work" How long since the last time it worked ? Have you changed the channel or encryption method since then perhaps? if no, then go to "change preferences of wireless…" link on the "view available wireless networks window" (by double-clicking the wireless icon near the time at the bottom right-hand corner of display.) Tallon41