Connections problems are not exciting. It is very frustrating to run into a connection problem when you are in the middle of something, and even more frustrating if you were doing an important task. It is normal to be frustrated, so the best thing to do is calm down and try to solve the problem.
The first thing you want to do is check if all the cables are plugged in. Did you accidentally pull a cable or disconnect the router? This may sound stupid, but it is a problem that occurs often.
The next thing you want to do if none of the following happened is to reset both the router and the modem. Go ahead and turn both of the devices off, and turn the modem on first. Wait a few minutes, and then turn the router on.
If this still does not work, you want to try connecting your LAN cable to the router or modem if you have not already done so. If the problem still persists, the problem is most likely with the service provider.
If you find that it is suddenly not working or you have a new device, make sure you did not make any network changes on your computer or laptop. If none of these apply to you, I would highly recommend calling your service provider!