We got a RULU in 12/2013. It worked for 3 months and now can not charge i

Some tablet brands will not recognize certain charger brands or connections.
First, try all available connections-USB-wall inverter, and direct computer connection (making sure the computer is awake and logged in). Second, try restarting your tablet. Third, try gently wiggling the connections on both ends, to see if it recognizes a charge. Finally, leave it plugged in for a few hours, even if it says it isn't charging. You may have a trickle charge-to put it simply, the cord is not giving the device enough power to qualify as a charge, but there is power traveling through the cord. If the charge level goes up a little over that time span, you have a trickle.
If these don't work, just purchase a new charger. They're sold everywhere-Wal-Mart, Target, Best Buy, 7-Eleven, name a store and they probably sell USB charger cords.
I hope I helped.