No LAN Connection.

I'm new here. I just recently bought a wireless network kit from Netgear model series wg111. It came with the router and usb card. Everything was working fine for about 2 days, except yahoo was really slow or not working. My ISP is SBCYAHOO DSL. I found out that I had to adjust the MTU. When I adjusted it to 1400 it worked for yahoo but it was slow to download all , but I called Netgear for help and they had me reset my router and adjust the MTU. Well, now it says network cable unplugged under network settings for the LAN. I can use the internet just fine, but I can't play Playastation 2 online. How do I fix this?!

Here is some info on my side: Windows XP, Netgear wireless kit with usb card, Dell dimension 3000 pc 2.8g 256mb 80hard, ISP SBCYAHOO DSL, sbc modem speedstream 5100(not the 5100b).