Hi this my first post, I made this account to tell you how to fix the HDD error, this is because you may have just pulled it out and corrupted the format. To fix it all you have to do is type:
diskutil list
Hit enter and then find the disk number, for example /dev/disk[Number Here].
In Disk Utility you can't repair it but in terminal you type in the command:
diskutil repairDisk /dev/disk[Number Here]
It should say
"Nonexistent, unknown, or damaged partition map scheme
If you are sure this disk contains a (damaged) APM, MBR, or GPT partition map,
you can hereby try to repair it enough to be recognized as a map; another
"diskutil repairDisk /dev/disk1" might then be necessary for further repairs
Proceed? (y/N)"
Hit "y" then enter
It should then say
"Partition map repair complete; you might now want to repeat the
verifyDisk or repairDisk verbs to perform further checks and repairs"
Now check and see if your HDD and your contents are on your desktop.
Hope this helps
Edit: After this, go into Disk Utility and then verify your disk
diskutil list
Hit enter and then find the disk number, for example /dev/disk[Number Here].
In Disk Utility you can't repair it but in terminal you type in the command:
diskutil repairDisk /dev/disk[Number Here]
It should say
"Nonexistent, unknown, or damaged partition map scheme
If you are sure this disk contains a (damaged) APM, MBR, or GPT partition map,
you can hereby try to repair it enough to be recognized as a map; another
"diskutil repairDisk /dev/disk1" might then be necessary for further repairs
Proceed? (y/N)"
Hit "y" then enter
It should then say
"Partition map repair complete; you might now want to repeat the
verifyDisk or repairDisk verbs to perform further checks and repairs"
Now check and see if your HDD and your contents are on your desktop.
Hope this helps
Edit: After this, go into Disk Utility and then verify your disk