Network Cable Unplugged Issue

[phufool]

I live in a college dorm and my internet used to work fine until I used my friend's ethernet jack in his dorm. He uses a "switch" that allows more ethernet jacks to be plugged in and I think this messed up my Local Area Connection somehow. Now when I try using the ethernet jack in my room it says "Network cable unplugged" even though I know it is plugged in and is working. The internet works fine if I plug it in my friend's jack though. Anyone know what I can do to fix this? This happened before and I messed around with the Speed & Duplex Settings and it worked... but now when I try that it doesn't work anymore!

Now instead of "Network cable unplugged" it says "Enabled" but the wired connection isn't working still o.o
This is on 10mbs Full Duplex
Actually... it switches between "Network cable unplugged" and "Enabled" or "Unidentified Network" depending on the Full Duplex Settings.. but it never works