|When is disk management look at how the drive is configured there. |
You mentioned this is a backup drive. Does that mean the files are also on the internal drive in your computer? If not then that isn't a backup but the primary copy. That is an invitation to lose valuable data.
You are fortunate that the drive still shows. That is an indication the drive is still functioning.
You may have improperly removed the external drive without using the safely remove command.
If that is the case then it may be possible to rebuilt the partition using a program called testdisk. Testdisk may work or it is possible it could make matters worse.
you may want to first use file recovery software to copy the files from the external to another location. You can use a live version of Linux like Knoppix or Puppy or use file recovery software. Look at the links below for recovery software and to the testdisk site.
PC Inspector (freeware)
Zero assumption Recovery
The demo is limited
It will only recover 'up to' four folders per run
But you can make multiple runs
IMO the best, but not free