I lost my follower. Is there a way to find it? When I try to have someone else follow, they say I already have one.

/bump

Sometimes if you fast travel or take a carriage ride to a distant location a stuck follower will show up at your side when you arrive. If it's a follower who is waiting somewhere they will eventually get bored and go home and the game will announce that your follower has returned to his home. Stray dog and Meeko do this a lot. If that doesn't work, maybe you can return to where you were when you lost them and find out why they are stuck. If all else fails, hope you have an earlier save from before they got lost.

If you play on a PC there are console commands you can use to summon the follower to your location. I assume though that you are playing on a console, in which case if going through doors or fast traveling doesn't catch them up with you you may have to load a save from before you lost them.

Best to let us know what platform you are on, what follower it was, and what quest or circumstances you were in at the time.

There are a few followers that I can think of that can do that bug.

Marcurio, Torvar, and Uthgerd the Unbroken is the most common.

i'm on pc.

And who was the follower?

What is the command to summon a follower?

Jessa

Assuming you mean the dark elf mercenary, Jenassa (I don't know of a Jessa) ...

enter the console and type the following two commands:

prid e1ba9
moveto player