Didn't eject my external hard drive now it will not reconnect

I did the same and was able to see it in Utilities, but not mount it. I read this article and followed the steps and it fixed the problem http://osxdaily.com/2013/05/13/mount-unmount-drives-from-the-command-line-in-mac -os-x/

Utilities - Terminal

Type: diskutil list to find your drive (mine is disk2s2)

Unmount the drive: diskutil unmount /dev/disk2s2

Mount the drive: diskutil mount /dev/disk2s2

The drive immediately appeared on my desktop allowing full access with no damaged files or corrupt disk.

Well in all honesty even on a PC you are supposed to properly Eject an external before you disconnect it. Even if you think the drive is not being accessed anymore it still may be by the OS. Just unplugging it can corrupt the drive.

Try doing a complete Power down of the Air then a Restart. Power down the drive if it has its own AC power source and then power it back up and connect it. If it still doesn't show up then it is the Air that has the problem.

By the way how is that drive formatted? NTFS or FAT32?

I don't know what is happening with hard drives but I had a very same issue. I tried restart and everything else the HDD was visible from Disk Utility(without information about owner, and space on the disk) but in finder I couldn't find it. I tried to connect other operating systems with the same HDD and Linux couldn't also see the drive than I connected it to the windows there everything was fine after connecting to windows I reconnected to my macbook air and woalaa it works.

I don't know if this will be helpful for someone but for me it worked.

Have you Re-Booted the Air? If not give that a try first.

Oh and if you didn't know Apple has a 14 day No Questions Asked Return policy for full refund. So If you find the Apple Mac computers are no better then Windows you should return it for full refund and buy a Win PC. I say stick with the Winners. The World Runs on Windows.

And this same drive still works fine on a PC? If so you have run into the Apple Mac Black hole. Something just don't work on a Mac. Even if at one point they did.

Try connecting the drive then Open Disk Utility and see if the drive shows up there. If it does then for whatever reason the Mac just can't see that it is actually formatted in a way the Mac can read it.

Also if this a USB powered drive you may have to Reset the SMC. Mac's have a real problem with USB powered drives. And they tend to Turn Off the USB port, or ports, if it senses a device drawing to much power.

Having the drive formatted NTFS should not have any effect on whether the drive shows up or not. OS X can Read NTFS formatted drives, it just can't write to that format.

Well you do know that Apple Mac's are not immune to problems, just read these forums. So if this is a New MBA you may want to return it for another that works correctly or something else. Apple has a 14 day No Questions Asked Return Policy.

Good Luck.

You didn't eject it and just pulled it out, it can cause the drive to become corrupt,

what you have to do it open disk utility, and under first aid tell it to repair disk.

Always Eject Hard Drives or you could loose everything!