I think either your NIC is dead, or we're on a dead port on the router - or the cable is shot.
Swap ports on the router, see if it comes up. If it doesn't, are you able to swap the cable? If you test with a different cable and still no go. I'd be 20 bucks the NIC died.
Flashing lights aren't software based - that's 100% hardware based. I get them on machines that aren't even powered on - it's a network connection saying 'hi!'
*** edit
Heck, boot into the bios. Your nic will flash if your in the bios, no nothing. If it's not flashing we're down to physical issues.