Hi Matteo,
My name is Igor, I have 12 Microsoft MVP awards. It's a pleasure for me to help others and I'll do all my best to help you. I'm sorry you have a problems.
It is more effective to ask such questions at Q&A forum https://docs.microsoft.com/en-us/answers/index....
It is oriented to admins and corporate users, and this forum - to home users so local experts may have no corresponding knowledge, sorry.
However, you may try ro run Microsoft .NET Framework Repair Tool - https://www.microsoft.com/en-us/download/detail... or use method described at https://support.microsoft.com/en-us/help/306160...