if he had reset the router, you must setup it again: connect your pc to the router by cable (a top-end one could have a usb connection). Open your internet browser and go to 192.168.1.1 (standard factory default adress for routers) If you are lucky you will not need a password. If not, you must find the pass on web (search on forums or send an email to the manufacturer).
Once opened the page you will have to follow a menu for seting up your network. But here, again you will need some knowledge about networking.
Good luck