I agree with Siempre.
Take the phone to your carrier's store, and see if they will let you test it with a new battery. If you can charge the phone no problem, then you have your answer.
The other problem could be that after 2 years of service, the micro USB charge port on your phone is worn out. I had a Galaxy S and a Galaxy S2 that both had this problem. After about 2 years of faithful service, they both could no longer charge using the USB port. If your phone is doing this, your choices are get a new phone, or get an external battery charger, and use that to recharge your battery.