Mystery Internet

We have two computers connect to the internet via Netgear router model MR814v2. Suddenly a couple days ago one of the computers ceased to be able to connect to the internet, while the other still can. No settings were changed on the broken PC, so I am confused. I tried turning off the computers, the modem and the router and then turning them on in the opposite order and that didnt help. If anyone knows any other sites that would help or if you have any help, it would be appreciated.