Help with internet connection

Hello all, let me tell you right up front that I am not overly knowledgeable about computers so if you can speak to me on a third grade level I would appreciate it

Problem: I have three computers in my house. Two of them are connected to a router, the third I set up using a wireless usb adapter which worked fine. Now because of work I had to hook up that wireless usb computer directly to the router using an ethernet cord. I unplugged the wireless usb (can't use wireless because of work btw) and hooked up the ethernet line. Now I can't get on the internet. I tried everything I could think of including rebooting the router, rebooting the computer and releasing and renewing the ip address. This computer has worked before with this setup but that was before I had set up the wireless usb. Any thoughts of what is happening? I can only imagine it was something with the original setup of the usb but I can't think of what it might be.

Any help would be appreciated. And remember "like a third grader". Thanks

FYI all the other computers can connect to the internet.

FYI x2 No firewall is running on the computer I'm trying to connect at this time.