With any router, you should be able to rest all the settings, by using a reset switch somewhere. (Usually you'll need a needle or pencil to push it in) However: beware - you need to type in all the details again for you ISP and so on, including the password. Check these with your ISP first if you're not sure.
Then: write it down and stick it somewhere else (preferably not on the router or anywhere near the computer so others can't find it).
Eric Davey, March 2010