Accidentally unplugged the external drive, then OS X won't mount my external at all. Disk utility shows my hard drive. but the partition is greyed out. Running first aid, verified the disk showed me some error, but repair failed/ However, booted my Mac Mini to Windows 7, plugged in, Windows immediately recognized my drive and mounted the drive. I am able to open the partition and copied all my files to a separate drive. Then check the disk, Windows did not find any errors. The drive is exFat formatted to ensure the maximum compatibility between Windows and OS X. Now this really sucks. I am using OS X as my primary OS and use the external attached to Mac Mini as downloading drive and storage drive since I only have 128GB SSD as my main drive. Can anyone suggest any way to mount this drive on OS X?