I have a My Passport external hard drive but it won't connect although it shows up on my desktop.

You may be able to investigate the external HDD, by use of Disk Utility;

this could help to see what format it may contain, or reformat to use it.

Disk Utility User Guide for Mac (Table of Contents) - Apple Support

//support.apple.com/guide/disk-utility/toc

Sometimes an external drive may fail, &/or if un-mounted incorrectly, it

may cause an internal fault with the format; & might never work again.

Passports have been the subject of many similar posts here for a long time. Although WD bare drives are quite good, the little low-cost enclosures like the the Passport seem designed to go on sale every other weekend.

The usual issue is that the Passport, like all "go on sale" drive enclosures, is bus-powered. That meas that, instead of bringing its own independent power source to the party, it parasitically draws all its power from the computer's USB ports. At some point that becomes not enough power.

Ultimately I prefer you move to a higher-quality enclosure but, for now, here are some things to try:

• If you are connecting the Passport through a non-powered USB hub, test by connecting it directly to the computer's USB ports.
• If you must use a hub, get a POWERED hub. They have independent power supplies that usually satisfy the demands of bus-powered drives like your Passport. Example ---> here
• If you can sacrifice or relocate the data currently on the Passport, use Disk Utility to see how the Passport is formatted. If it is NOT formatted for Mac, may it so.