You'll need to verify the problem is not the USB cable, not the USB port on the computer, and not the computer. Then see
What to do next if Jl Cmder will not connect and wipe - BlackBerryFAQ.
It is a process of elimination. Your problem could be hardware, something broke or failed. If you exhaust all other possibilities, and you are unable to wipe and reload the software, that is what will be left to conclude.
Also, be aware that some have had to repeat the procedure at the link above a number of times to make the connection. If you have to use that procedure and it doesn't work, try again.
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