Power off both the PC and the router. Then power on the router followed by the PC. Does it connect at 100 Mbps? If not, is it set for half-duplex or full-duplex? If auto doesn't work, then try setting the speed and mode manually.
initially th e setting was on auto detect, when we were nit able to connect with network we were froced to set on 10Mbps full duplex now it is working on the same setting.
still we wondering if the original setting can be restored ...