External Hard Drive (Seagate 2TB) showing as not mounted

Sazzarocksdahouse wrote:

I was doing ,my regular Time machine backup and it failed and wouldn't restart. In the end I had to force eject the drive and now Finder won't show the drive.

I've gone into Disk Utility and the drive shows but greyed out. First Aid won't run and it's showing as unmounted. If I try to Mount it, will that erase all the data on it? In any case is that the only possible solution?

If that doesn't work I have another drive but that has backup from my previous MacBook. If I start using that will I need to reformat the drive and so lose all the 3 year old files?

I'm on 2017 MacBook Pro Touch Bar all up to date and running Catalina - plenty of room on drives and in iCloud.

This is a good indication the drive has failed.

If you need to create a new backup from Mac—https://support.apple.com/guide/mac-help/if-you-need-to-create-a-new-backup-mh34042/10.14/mac/10.15

Your best bet with Catalina is start a new Time Machine backup. Even if this mean erase/reformat the external for a fresh start and an empty Drive. GUID/HFS+

Types of disks you can use with Time Machine on Mac - Apple ...

https://support.apple.com/guide/mac-help/types-of-disks-you-can-use-with-time-machine-mh15139/mac

Backup disks you can use with Time Machine - Apple Support

https://support.apple.com/en-us/HT202784

Back up your files with Time Machine on Mac - Apple Support

https://support.apple.com/guide/mac-help/back-up-files-mh35860/mac