I use a 500 gb Seagate Go Flex hard drive. Was working fine till last night. When i plugged it in today, the lights flickered on as usual, the computer recognized it with a beep, assigned it a port (L) but after that it refuses to open. Everytime i try to open it, the msg bar reads 'File directory unreadable or corrupt'.
Disk management states it to be healthy (primary partition)...Properties reads Used and Free space to be 0 bytes.
This is an unbelievably common occurrence, as a scan of old posts on the topic will show, often it is due to the master boot record on the external drive getting corrupted by a shutdown before a final write is completed. Those drives should come with a giant sticker that says -- "don't trust your data to me for backup."
I usually start by trying other ports and computers, but usually without success. You can also check in disk management to see if Windows will let you change the drive letter, as that can fix the issue. I have also on occasion had success with uninstalling the USB port and then rebooting so that it reinstalls -- with the external drive not attached during that work. If it shows up in My Computer you can also run a disk check on it but going through the properties tab. Next I would try to a freeware program like Recuva in an attempt to salvage any of the data.
From there it depends on how important the data is and whether you have another backup so that you can just reformat.