All my mods poofed

[Sonlight]

I am still subscribed to them all but they don't show up in the mod list. what happened?

[Distman]

Reinstall Rimworld?

[Kirby23590]

Log off steam and then Log in again?

[Pelador]

One explanation:

Check your game options, by default the game is set to remove all mods back to "core" if there is a critical error on load. There likely for a good reason though.

This is just to explain that if a critical error occurs when loading the save and for instance gets stuck into a loop then this feature resets everything.

If you have a mod manager mod then you'd be able to load the mod list back from the savegame and modify that listing, assuming it's a situation where you can remove mods that won't ruin the saved gameplay too much. But if the critical error on load occurs on initializing before the world generator then it doesn't really help you. But if it occurs on world gen etc, i.e. loading a save then you'd then be able to reload the mod list and start removing mods to find the culprit. This assuming that the error messages associated don't make this easy for you to identify where things are going wrong.