Delete the "network connection" on your pc, reset the router (if I remember correct, think you have to hold it in for 5 secs ) and start all over again.
ie, set up "new network connection".
I know it's a pain, I had to do it here a few months ago. If you don't have any "paperwork", Linksys website is really good.
Good luck and tell your buddy to keep his paws off it.