Linksys hijacked by a Laptop

Not really sure if anyone can help because I have so few details, but here's my problem.

A roommate and me set up a secure Linksys network (ie yes, it did have a password). Well, someone else just moved in and wanted access to her laptop, so my roommate gave her the password. I think our new roommate must have done the setup wrong, because for some reason she also had to input the Router Ip number... which none of us had to do. Anyway, now the system is hijacked and we cant figure out how her laptop got rid of our network and replaced it with its own. I can't even find settings for a network that she may have created. The only things I found that might be able to create a network would be a HP Wireless Adapter program or Athenos, but I don't know what exactly those programs do. To make matters worse, the stupid laptop set up a password that we can't figure out.

We tried to uninstall Linksys from our computers and reinstall it, but at first it said the router was being used by another system or something similar. I hit the reset buttom several times (over 30 seconds) and now the setup can't find the router at all.

Anyone experience something similar or have any idea how to fix it?

aceswild