You should never rely on a single drive to store your data, as that means you don't have a backup of it in case of hard drive failure (and all hard drives fail sooner or later, as sure as night follows day). You need to keep at least two copies of it on separate hard drives.
If the drive cannot be detected there is no way to recover the data yourself. Your only option is to send the drive to a data recovery specialist if you can afford the cost - - it ain't cheap.
It's a long shot but you may want to try a new data cable first.