I'm not sure if this goes here or not but oh well.

I can't use any of the activities from any mod right now. In skirmish, only the vanilla actors show up. Any advice?

What did you last do that made it stop working?

I think it was either attempting to use the mod manager or it might have been one of the mods.

Do you mean that only vanilla actors show up?
Cause if you did, then it's because the SKirmishActivities.ini was not commented out in missions.rte

But the problem is that it was like that before.

Here is a timeline for you:

1. Vanilla in Skirmish only. No other mod's activities works.
2. Went into Base.rte to see if there was a problem, none
3. Went into missions.rte, saw that it was commented out. Uncommented it.
4. No solution...

Easiest fix, reinstall Cortex Command. It should fix anything that got broke.

Mod Manager is a devil. It screwed my copy pretty bad. I think it's easier to just modify the .ini's.