It could be router and modem combination. Is there any other PCs or laptops in the house? if not and this is the only one. Turn off in this order, laptop first, next router and last modem, last 2 you can simply unplug from power. Leave it unplugged and turned off for at least 15 minutes - router and modem reset. When starting connect or turn on modem first, give some time to boot completely, next same with router, when everything ready - start your laptop.