Accidentally deleted nether from files

Accidentally deleted the world file for Nether in my plugins (I know, don't judge)

After, players can't access the Nether through portals; it doesn't teleport them anywhere.

How can I re-add the nether?

I am using MultiVerse.

If I do import, would I have to create a new world first or could I safely to /mv import (whatever) in my lobby world?