Computer Won’t Connect Via Network Adapter?

First off I am running Windows XP SP2. I have both a network adapter connected to a router which goes into the modem via cable and is a much faster connection, as well as a wireless adapter which is fast enough for internet not fast enough for games.
Well this morning I turned on my computer, keeping in mind last night everything was fine well this morning I cannot get the internet through the network adapter no matter what I try. It says I have limited or no connectivity because the network did not assign a network address to the computer. When I try to repair it says it cannot renew my ip address .
There is another computer on this network, it is working fine so I tried bypassing the router, then tried the cable from that computer on this one. Nothing worked. I updated the driver on the network card, which is a Realtek RTL8139/810x Family Fast Ethernet NIC, but it said there is no update available. I found a website that told me to change the speed and duplex from auto to 10mbps full duplex, and for just a couple minutes that actually worked. But then it went back to no connectivity again. After that I tried a system restore back a couple days but still nothing. Finally I hooked up through the wireless and here I am.
I'm not terribly computer savvy, though I can usually fix problems myself I am having a terrible time understanding all the jargon on the tech websites so if anyone can help me kindof dumb down your answers please lol. Thanks in advance!