My Blackberry Wont Charge Or Open On My computer?

[Lui]

Ok. Well i bought a blackberry curve about 2-3 months ago and it was working great. just a couple days ago my battery was running low so i connected it to my wall charger.(left it for a couple hours) come back and its not charged. I took out the battery and put it back on, connected it, it would only charge for a few seconds (the red light will come on then go off).I thought it might be the charger, i went and exchanged it for the same one but still no charge i went again to at&t and the guy charged it for me with his charger a cheaper one it worked. My cousin has a blackberry too, i asked her to try my original charger on her phone, it worked perfect so i knew it wasnt the charger.My blackberry also used to charge with my computer and xbox 360 now it doesnt. my computer wont even read it no more so i cant put music, pictures,videos, etc...the battery is not the problem i asked already nor is my usb? what can i do?