Script doesn't exist+MonoBehaviour has unknown format

When I try to attach a script to an object, it tells me script doesn't exist. I looked at similar problems and started screwing around with some stuff. I ended up clicking add component from the object's inspector to make a new script, which unity yet again tells me doesn't exist. Yes, I am saving these before the message comes up. Then I tried changing the attached script and got the message "MonoBehaviour has unknown format!:"

 

There must be an error on the script this means it doesn't save in a way unity will read it so post the other errors

 

Sorry, I posted all the errors available, you can even see the console in the bottom left of the screenshot.

 

If there is no error on the script then maybe its a internal error.

 

I made this script while following a video tutorial found here:

What I have is shown at 25:17, so I am sure it isn't that.

 

This can happen if your class name does not match the file name

 

This was happening to me because I had prefabs that had missing scripts. The prefabs weren't even being used in the game but this still caused my build to fail.