So it was running low on battery, but it was charging, and it turned off all of a sudden. Now it won't turn back on.
Help?

How long did you charge it for? If the battery is totally empty, it won't turn on for a few minutes.

well it was charging when it turned off.
I had been charging it for about 15 minutes when it turned off.

Now, it still hasn't turned on after more than an hour of charging.

How old is the battery?

Hope you were using your blackberry charger, anything else and you could run the chance of the phone being cooked.