It's a Samsung HX-M500T CB/GWhat brand is your external? You might be able to run a program to check for errors and it may fix them to where you can access the drive.
So yesterday I did this using that Software I clicked the Advanced tab then can't remember what I clicked and it's not coming up now but it did a long test and said "Passed". Does this mean no issues?You'll want to download and run seatools.
SeaTools | Support Seagate US
SeaTools - Quick diagnostic tool that checks the health of your drive.www.seagate.com
The first link on that page. Run the extended test.
What will a data recovery company be able do that I couldn't?Well that's good at least. Drive is physically ok, but looks like it got corrupted. Try check disk.
How to Run CHKDSK on External Hard/USB Drive - 3 Steps - MiniTool
Detailed guide for how to run CHKDSK on external hard drive or USB drive in Windows 10. Also learn how to recover data from external hard drive or USB drive.www.minitool.com
If that above doesn't work you'll need to get a data recovery company involved if that's worth it to you and the data.