Can you ping the gateway on the network? Does your computer have an address that belongs on the network where connected? In other words, is the address assigned to your computer one that should be able to communicate with other computers on that same network? Does your network interface card show a LINK light showing connection status? Is the NIC configured with the same duplex/speed settings as the LAN switch port it is connected to?
Yes, check the IP of your computer first, that will tell you a lot right there. If you run IPconfig at the command line and you see an IP starting with 169 then you are not talking to the network at all. Tell us what you get when you run IPconfig and then what troubleshooting you have done so far.