General Networking/Lan/Wan/Network connection
I have a Windows XP computer that I want to connect to my home network. The RJ 45 connection keeps giving me "A network cable is unplugged" message, and I cannot get a wireless USB adapter to work. Can the computer be connected to the router by USB?
Sorry - no it can't be connected to your router via USB. Only via wireless or Ethernet. Technically the answer is actually yes - but it is very complicated and not supported by normal routers. Really it's not worth thinking about.
You mentioned that you can't get a wireless USB adapter to work, and that your direct Ethernet also seems to be having issues. May I assume that you have tried more than 1 port on your router and also tried more than 1 cable? Sometimes these things ARE a cable issue - or even that a single port on the router can be bad. So it is worth it to try different things and keep track of them. Also download the latest driver for that USB adapter - often the newer drivers work better than whatever came with it on a CD.
So let's figure out if maybe it is your PC, and not your router. I hope this is a laptop and not a desktop :-) Take your PC to somewhere else - a neighbor's, Starbucks, whatever and try and connect there. If you can connect someone else but not home then the issue is isolated to some issue with your router.
Please try isolating things and let me know what does and doesn't work and we'll take it from there.