Laptop Lost Connection to Network

This is an old IBM Thinkpad (Win 98se), which, until today accessed the internet via a Belkin PCMCIA ethernet card connected to a Linksys wired router. It was also set up to share files with another PC (XP Home). The router is connected to the internet via a cable modem. There are also 2 other PCs which connect wirelessly through a Linksys WAP. When I couldn't connect to the internet from the laptop, I checked the other machines and they all could connect fine. After restarting the laptop and rebooting the router, the problem continued. I checked ipconfig and found that the IP address and subnet mask were showing zeros and the space next to "default gateway" was blank. I also tried a different ethernet cable hoping for a good old fashioned defective wire but that was not it. The indicator lights on the connection to the card (labeled "link/act" and "100") are both lit. I attempted ipconfig/release and ipconfig/renew but there was no change.
Does anyone have any ideas?

First lets make sure the network card is working properly. In the command prompt type: ping 127.0.0.1 which is the loop back address for the card and should return (4) Reply from 127.0.0.1: etc. If by chance you don't get 4 replies you may have a bad network card.

If you do get a the 4 replies then try to type: ipconfig /release then when it completes type: ipconfig /renew and see if the router hands you out a new IP address.

This should get you started

Thanks for helping me out. Unfortunately, I didn't notice your reply until about 8 hours after it was posted because I gave up on looking for one since it had been several days since the original post. Pinging 127.0.0.1 resulted in 4 packets being sent and received with 0% lost, but ipconfig/release and then ipconfig/renew had no effect. I still have zeros for the IP address and the subnet mask and nothing next default gateway. Since the original post I also uninstalled and reinstalled the network card and the driver, which did not work either. It does appear in device manager.