make sure your firewall is switched on 1st sometimes if you have shut down the night before you have to unplug your router power for 15seconds then replug the router power after that you may have to refresh your network connection from your PC. I tend to leave my router switched 24/7 simply turning off the PC and that is now late evening & switching on 0630am next morning
because when i did it, i got lots of viruses. the two times i rebooted my pc before that without being connected was fine. but rebooting for me whilst having an ethernet connection plugged in caused havoc.