Have you done a firmware (router) or BIOS update before your problem started?
Have you replaced your network adapter or installed a new firewall on your computer?
Is your network adapter on-board?
Have you changed some network settings in Windows?
Shows Windows the LAN connection in the task bar?
Have you tried to connect your network adapter directly to the DSL modem or have you tried to use LAN with one of your notebooks? Just in case the network adapter in your computer is broken
€dith wants to say: I should read your postings better
Try to replace your LAN adapter in your PC.