Network problems are definitely one of those things that ALWAYS happens at a bad time. You need to get to something, but all your are getting is Page Not Found - your Home Network is down. ##!!!&**%%$#@!! Alright, calm down, we'll fix this. If the connection was recently working and is not freshly installed, chances are you can get things going again w\out having to call your Provider or any support people.
First off, the steps you take will vary somewhat depending on if you are wireless or physically connected via an Ethernet cable to the gateway.
Scenario One - you are connected via a cable. First, check to make sure both ends of the cable are securely connected one end to your computer and the other to the home gateway.
If that was not the problem, reboot the DSL\Cable modem and the Home Gateway. Remember to leave them powered off for about a minute and power up the DSL\Cable modem FIRST. After that has been on for at least 30 seconds, then power back on the Home Gateway and let all the settings on both devices get cleared and refreshed.
Hopefully, between the two steps above, you are now back in business. If not, check this next. Look at the actual interface port on your computer or laptop. Assuming your Ethernet cable is plugged in, you should see a green light to the left of the plug and an amber light to the right - they could be blinking but don't have to be. If those lights are not there or happen to be red, then you don't even have a connection with your home gateway. At this point, you will need to focus on the gateway because there is nothing your computer can do if those lights are out or red (unless the network interface port on your computer is the problem, but that is another can of worms). Let's assume for this example, the computer's network interface card (NIC) is in good functioning condition.