How do I repair a hard drive that was being written to while my MacBook Air crashed? (Drive will not mount) My external backup drive will not mount. I have tried to mount it in Disk Utility via the app and the command prompt but the attempt times out. Any suggestions?

I backed up my HD the day before dropping off my Mac for repair, and then tried again just before going to my appointment. During this last and final backup my Macbook Air crashed. I have since discovered that the drive will no longer mount, likely due to the crash that occurred during the last attempted backup. I am unsure if the drive can be repaired.

My logic board was short circuiting some where that controls the headphone jack. Initially this prevented me from using the jack but eventually caused my mac to crash several times before I brought it in for repair. I believe that it is the this crashing that is responsible for my back up not being accessible but that my data may still be intact.

Thanks for any help you may have!
I'm assuming that the port in your macbook air has been confirmed to be in working condition. Another consideration is that the hard drive's port has been damaged.

Are you able (perhaps through a friend) to test the hard drive functionality on another mac or windows system? Even if you had to reformat on a windows system, that would (hopefully) get the drive functioning, and then you could thereafter reformat for mac.