My dad reset my router. 1 computer and X-Box Live can't connect to

He was screwing around and hit the reset button. Both Computer 1 (this one - where the router is based), our X-box Live, and Computer 2 (in another room) couldn't connect to the internet. We somehow got Computer 1's internet working again (obviously), but the X-box live and Computer 2 still can't connect to the internet. The router evidently needs to be re-configured or something - a friend of mine of mine came over and had a look at it and said that the problem was the router and the modem aren't communicating with one another. We've called Dell tech support or whatever and they are all a bunch of foreign people with knowledge less than or equal to my own. The router is a Dell 2350. Anyone out there with expertise in this area that can help? Would be greatly appreciated. Thanks!

1st thing would be to power cycle everthing down and then one at a time powering them back up. turn everything off, xbox, & PCs, then unplug the router, unplug the modem. wait at least 2-3 min. plug the modem in 1st, wait 2-3min, plug the router in, wait 2-3 min, boot the 1 computer that has internet. After that you can check the configuration on the router, I'll check for manuals on your router online and see if I can find one. Do you have manuals, documintation? on hardcopy or CD? Tonka