I suddenly cannot access the internet (LAN)

I suddenly cannot access the internet on my desktop conmputer over a LAN connection. I am now on a laptop using a LAN connection over the same router, eliminating an ISP or modem problem. I am unable to use 'ipconfig /renew' because it is "unable to contact your DHCP server." Also, I am unable to ping any websites, but it IS able to ping itself. There is no incoming or outgoing traffic it appears, but my modem says it is fine, and so does my computer(displays the connection as active and running). My firewall settings have not been touched since I was last online yesterday, and today it suddenly will not allow anything. Any help is appreciated!

I have reset my router and my computer and repaired the connection several times. Each with no help.

Thank you for your time,
Derek

EDIT: Just realized that my IP adress on the nonworking computer appears to be on another subnet? NSLOOKUP adds no help, everything times out. I have tried different ethernet cords, and realized that I am able to send packets, but not recieve any.

Are you supposed to be using a DHCP server?
Have you tried to manually set up the network properties.?