'Clams, here is the last ditch effort. If it doesn't work, you are buying a new router/modem:
1. look on the back or bottom of the router for a very small hole. It will be roughly the size of the end of a paper clip.
2. get a paper clip
3. straighten the paper clip enough to poke something with it
4. put the end of the paper clip in the hole you found in step #1 and hold it there for 5-10 seconds.
This will perform a hard reset on the router/modem.
The router will take a few seconds to go through it's start up.
After that is the moment of truth. Either it works or you are buying a new router.