External drives by their nature get mistreated a lot more then their internal counterparts.
The is heightened with HDD's as they have moving parts. And even a disconnected HDD with a parked head will not survive a waist high fall onto a footpath (been there - done that).
All drives go south eventually, that's why backups were invented.
A few things to double check - plug the external drive into another PC's USB port.
And also remove the drive from the enclosure and connect the physical drive into another PC's internal cables.
But, sadly as stated, you are more than likely looking at a dead drive.
If nothing already suggested bears fruit, you are looking at a data recovery process, either using free software like Recuva, or EASEUS Data Recovery, or Disk Drill, to name a few.
Be warned, these programs can take many hours to scan your drive and typically (in my experience) have a low success rate.
Your last resort would be a professional, forensic, data recovery lab - I've had feedback from people using these and prices have ranged from $950 to $3,500.
So the data has to be worth the expense.
And although the horse has bolted on this case - if you data is important, it needs to live in more than one location.