Some options:
a) Test the external drive on another computer
b) If you don't have another computer then see if you can find a friend, neighbor, relative, or local computer store to test the drive
If you've confirmed that the drive is ok, (no problems with partitions, no failures when tested) and it still does not appear post images for:
a) BIOS
https://www.disk-image.com/faq-bootmenu.htm
If it appears in the BIOS then post images of:
b) Disk Management
c) File explorer
d) Device manager > click view > click show hidden devices > expand disk drives and other devices > post images or share links into this thread
An additional method is to use a flash drive to copy and paste files or make backup images.
See if you can find a friend, neighbor, relative, or local computer store to borrow or purchase a flash drive.
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