ApplicationException: Unable to find a suitable compiler

Please Help!

I am making an app for android, and in the last 2 days, every time I save a new script or change something in a script I get this error:

ApplicationException: Unable to find a suitable compiler UnityEditor.Scripting.ScriptCompilers.CreateCompilerInstance (MonoIsland island, Boolean buildingForEditor, BuildTarget targetPlatform) (at C:/BuildAgent/work/7535de4ca26c26ac/Editor/Mono/Scripting/ScriptCompilers.cs:99)

I moved all the assets to a new project and the problem disappeared for one hour and then the problem appeared again...

If someone know what is the problem please help! I really dont know what to do...