My router wont connect to the internet

Hello, i have a netgear wireless router and up till about 3 days ago it stopped connecting to the internet. the wireless is green but the internet light is yellow. when i log into the router (the upgrade box pops up and says no internet connection) i dont know a lot about routers so all i do is click on things (DO not change anything) and it shows i do not have an i.p address..i was working fine 2 days ago but now does not work. can anyone let me know how to fix it

Thanks