Backstory:
Had to restart into a 2nd campaign the other day because my initial campaign completely broke where I was unable to launch any vehicles. Later I was reading here that you could revert to an earlier save before it bugs out like that and it supposedly fixes it, but it was too late and I had already started a 2nd campaign.
Problem:
On this new campaign, after playing for a day or so, I am now unable to save, load, or even launch any ships. The only way I was able to revert to an earlier save was by restarting the game and then from the main menu clicking load, but once I loaded any save I was no longer able to save or load anything, except for the pre-built ships (Which popped up but I didn't select any). When I press save button, either by pressing escape and clicking save or by pressing save on the top right. The UI proceeds as if it's saving something, but when I go into load there's no saves to load. I conceded and decided it was time to just start another new campaign, but now I'm unable to even start a new campaign. The UI pops up where I can select a flag and name the campaign, then when I hit start new campaign nothing happens, I clicked continuously on the start new campaign button and then all UI disappeared and I was left watching the Kerbal's floating in the background of the main menu.
What I Was Doing When It Happened:
After spending a good amount of time reconstructing a Saturn V with a rover I pressed launch, then realized I forgot to add some struts for stability, so I reverted back to VAB and then my game was ruined. Once I reverted back to the VAB my game was running at around 5-11 FPS (Usually I get at least 30 FPS, especially in the VAB) inside the VAB, using about 8-10 GB of RAM. Now I literally cannot play the game. (edited)