Well it can be lots of different issues.
First if you can what you will want to do is take the ethernet wire from the wall/or the modem and plug it directly into a device if that is possible. Make sure that the modem is passing traffic and you are able to get on the internet.
If you can not get on the internet try unplugging the modem and turning it back on after about a minute and try again If it still is not working and you can find a reset button, or pin size hole try resetting the modem. Once again try to pass traffic on a device plugged into the modem. If it still does not work the power surge could have messed up the modem and thus a phone call to your local ISP provider would be the next step.
If the modem is working, then unplug the router from power and then plug the ethernet wire back into the router and power the router back on. At this time you know the modem is passing traffic and the router should be able to power on and detect the traffic and configure itself back up and be good.
If you still do not get traffic try finding an ethernet wire and try plugging in a device directly to the router and see if it passes traffic. If it does then you will want to log into your router. More than likely being a Linksys you will need to open a browser page and where you would normally go to a website like google.com... you will type in 192.168.1.1 or 192.168.1.0 (sorry some routers have different variations) Then you will more than likely need to type admin in for the login and password in for the password. Or leave the password blank if that does not work.
Once inside the router you will check your wifi and make sure it is on and configured for DHCP and broadcasting etc. Or you can simply reset to default from within the router.
If the router is not passing traffic when plugged into it then you will want to find the reset button or pin size hole again and reset it. This will make you have to rename your network again if you changed it before and recreate your password but it should get everything going.
If after all that the router still does not work then you are more than likely looking at a bad router in which case you will have to find a place (Like BEST BUY!!!) to purchase a new router.
I hope that one of the earlier steps fixes the problem with your internet.
Agent Jeffrey A.
Badge 51747
Field Agent
Geek Squad Social Media Team
1/16/14