Unlike Paradox, Steam doesn't disable my mods (worst they've done is one marked as unlisted).

Go to the in-game mod manager and uninstall the mod (restart to make sure it's actually gone). If it is then find the mod on the Steam workshop, and subscribe to it there. It'll show up in-game after steam downloads it (might need to restart game).

Enable the mod, and play the game as usual.

There's nothing I can do about it. It'll be back up whenever someone at Paradox reviews/restores it. Feel free to complain to Paradox about their crappy automated take-down system or blame people spamming nazi mods in HOI4...

In the meantime you can:

• Log out of your paradox account from the main menu, and restart the game (be aware logging out means no mods will update).
  
• Play in offline mode?

The only visible means of contact on the paradox mod page is the report button, which (according to what I've been told) is mainly people asking questions or commenting on the mod.

Not actual bug reports, but thanks to the auto-takedown and manual review requirements means mods can be down for a little while (usually no longer than a few days).