Lost reference to unity library

When i open my project i see 999+ bugs like :

error CS0103: The name 'tranform' does not exist in the current context
error CS0103: The name 'Destroy' does not exist in the current context
error CS0103: The name 'gameObject' does not exist in the current context

When i open project file in visual studio i see that - https://ibb.co/pQvDmGS

"MonoBehaviour could not be found" How get reference to MonoBehaviour ?

 

Delete the library folder in your project directory.

 

thanks for fast answer ! ill try to do it but lost my scene settings and still VS cant understand what is a "gameObject"
I delete a Visual Studio 2019 and try to use visual studio 2017 and 2017 find half MonoBehaviour references but still cant work with "gameObject"