Network problems

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I currently cant access the internet from my computer. Previously I could, but had massively high ping and such. We (at my house) currently think that the landlord mightve used crossover cables in the house wiring or something else to cause the problem...but when I was messing with it i did not suspect that.

What i did suspect was my computer, so i played around, eventually rolling back the driver on my network card. This killed my internet instantly. Ive now used someone elses comp to dl a new driver and installed that. Still no internet. Any ideas??