Quick video on how to turn data (internet) connection on or off on your Android phone. A lot of people have this happen accidentally and do not know how to turn their 3G/4G back on. This video solves that issue! =)
This is a good troubleshoot to try if the internet is not working on your Android phone. This will reset the radios, and should fix the problem. If this method doesn't work, I'd suggest restarting your phone (or doing both).