JL_Cmder for blackberry, the javatool for blackberry which can help you to recover a crashed blackberry might be your last resort to get your blackberry back to life.
After having downloaded the JL_Cmder utility for blackberry, connect your blackberry with the USB cable to your computer (you can find the link to the download on the bottom of this page) you will need to run the JL_Cmder.cmd file
On the first screen you will simply press a random key to continue the process. You will then be asked in the second JL_Cmder for blackberry screen if your device is protected with a password, choose yes or no (press Y or N).
When you have chosen Yes you will need to enter your blackberry device password in the third screen. You will then be redirected to the fourth screen, if you have chosen No in the password screen, you will automatically be redirected to screen nr 4.
Now to recover your blackberry OS, press "4" and don't panic when you see the red screen, this is normal! it will just warn you that your complete blackberry OS will be erased. following the blackberry tradition, you will need to type the word "blackberry" to confirm erasing the blackberry OS.
After having completed this step, your blackberry should be completely cleared and ready to be reinstalled with the Blackberry OS release for your provider and downloaded from the official blackberry website.
Notice that JL_Cmder for blackberry should be used as a last resort only when all other means to recover your blackberry have failed. Mistakes or even the smallest issue might "brick" your blackberry (= unusable)