hey there could you just try something to see if your trackpad still senses your finger. unlock your phone and move your finger over the bottom half of the trackpad and see if a small light appears in the top middle of the trackpad.
no problem. this tells me that your trackpad doesnt sense your finger moving over it. i dont think its broken as you said it just stopped. one thing you can try is push down on the trackpad then pull the battery out when holding it down, once pulled just push for a few seconds then put your battery in and see if that works after its booted.
another thing you can try is get a piece of paper and put it on a flat surface then put the front of your phone on the paper and rub the trackpad on the paper a a fair few times then take the battery out push down on the trackpad not too hard but not too soft then put the battery in and see if it works once loaded
I think there might be a loose conection. I would consider trying to get it sent for rapair to make sure as this doesn't sound like the normal problem. I'm sory I couldn't help but if you want you can try ask the support for blackberry on twitter good luck