External Drive Shows Up Then Disappears

I have a 3TB drive that was working fine, but the power went out. Now when I plug it in the drive shows up in my computer then disappears. It showed the right drive letter as well as space. I was able to open it and see my files, but then the window closed and the drive disappeared from the drive list. I checked the disk management and it shows up with the right detail, but no drive letter. I am using windows 7.

Can anyone please advise me how to fix this? Thanks!

Hello,

It is possible the partition is corrupted. So i recommend you try using a data recovery software to recover you files and then format the drive in order to use it again. You can also try assigning a drive letter.