external drive does show is it the disk?

Where doesn't it show, in the sidebar or on the desktop? or somewhere else.

not necessarily,

you can stop external devices from showing in the finder

Finder>Preferences/General

but if that is enabled does the drive show in Disk Utility?

Does it show in the terminal if you open Terminal and type "diskutil list" w/o the quotes?

See mount section in 1st linked article.

Disk Unmount Using Terminal

Disk Utility – Force Mount Disk