You don't say whether the router is wireless or wired. For a wired router you reset to factory defaults and then setup your ISP settings**. If it is wireless you will also need to reset the security settings - SSID, encryption and MAC address access list.
Some routers allow you to backup the settings, if you can it is a good idea to do so. Either that or print each page of settings and file away for the future.
**This assumes that you used the default settings on the router. If you changed other settings as well eg IP address range and used fixed IP addresses for your PCs ensure that you know what that range was before you reset the router. If everything is working OK now you may want to defer the job to when you have time if you hit snags.
Last edited by srobarts; 28th September 2009 at 12:57.
Reason: adding info