It sounds as though you might have deleted some critical files either by accident or deliberately. Have you been trying to clean up C: by simply deleting files? Alternatively, have you been removing software you don't think you need?
The fact that it cannot find the necessary software suggests that it has been removed from the PC by something.
Either you have to track down the XP driver for your Ethernet adapter. If the adapter is built into the motherboard, then you may have to see if the [unnamed] manufacturer has a driver on their website for your [unidentified] model of PC.
When this happens to me I normally make an image backup of C:, then restore a known working backup I made before my problem appeared. If that doesn't work, then I know it's a hardware fault.
When you tried "uninstalling it", how did you do that. Did you actually uninstall the driver in Device Manager, or did you use the Application add/remove option in XP's Control Panel? If you used the latter route, then the software will have gone. If you removed it in Device Manager, then it should normally reinstall on a reboot.
My final suggestion would be either to add a USB to Ethernet adapter or a USB wireless adapter if you can find one with XP drivers. That should allow you to get onto the Internet where you could try one of the driver update sites to get the missing driver reinstalled.
I hope this helps.