It could be a few things. First, did you try charging it while it was off, instead of on? I ask because if it was completely drained dry you would need to leave it charging way longer than you usually do. The batteries are not really meant to be drained completely. See if will charge that way. If yes, then there are other issues.
Second, have you tried replacing the battery? They do go after a while, some sooner than others. If the battery is bad, it won't charge, no matter how long you plug it in for. If the battery isn't bad then we move onward.
Third, check if there are any stuck buttons or stuff stuck in with the buttons (food, lint, dust, etc.). If so, this can cause the drain, while it is trying to charge. If it charges then...