I was watching movies on my external hard drive last night and when i went off to bed i ran a defrag on the whole pc. However this morning when i switched everything back on the pc recognized that there is an external but i cant seem to retrieve the data or see the drive under 'computer' where all the other drives are listed. The external is plugged in and goes on but i cant read the data HOW CAN I FIX THIS please assist
PS I did try to plug the external into another pc and it is doing the same thing
The safest route would be the second direction, because a file recovery program like GetDataBack (which I had success in the past) won't change anything on the drive, it just reads it sector by sector looking for indicators of files and directories. If it finds them, it generates a browsable tree, which allows to copy the files to another drive. Feel free to ask for more info if you go down this way.
The partition recovery is quick. See the tools mentioned in the Wikipedia article. If it is successful, it gives you back the filesystem as it was, and there's no need for copying. However, it does commit writing operations on the disk, so it may reduce the chances of the file recovery if it proves to be unsuccessful.