Hello! My name is John, a self-employed tech, and I'm offering my time in good faith today to assist you on this question.
Make sure you have downloaded and installed the latest version of iTunes before attempting this:http://www.apple.com/itunes/download/
* Connect the iOS device to the computer with iTunes open
* Turn off the iOS device (hold down the sleep/wake button on the top) until you see the red slider and slide the red slider across to the right OR until the device simply shuts off, if locked up.
* Hold down the sleep/wake button AND the home button (on the front) for 10 seconds
* Release the sleep/wake button but CONTINUE to hold the home button
* iTunes should pop up and tell you it’s found a device in recovery mode, click ok and continue along for the restore
If it doesn’t work the 1st time, start from the beginning and try again.
When the device is in DFU mode, the screen will be black. If you see the iTunes logo on the screen then you have gone into recovery mode rather than DFU mode.
After the above, you may try jailbreaking again, if you wish...
Hopefully, this info will answer your question. If it does, please click ACCEPT so I can be credited for assisting you today. If you continue to have questions on this topic, do NOT leave negative feedback, just reply back to this ticket. I will be more than happy to work with you further, even after you click Accept.
Note: When leaving feedback, please judge only my personal efforts. Do not leave negative feedback for factors outside my control; such as hardware defects that must be physically repaired (obviously, not my fault), loss/lack of software or backups, or the JustAnswer website. It would be unprofessional to sugar-coat a solution and I show my respect by being upfront with you. Thanks again!