Unity 2017 just broke my game entirely

Every script has been replaced with ‘nothing selected’ in the editor and I cannot add any scripts to anything. It claims they aren’t there, but… they are. I haven’t changed anything. I opened my project to check something. Then closed it without saving. When I opened it again, every script was allegedly missing and nothing works any more.

I can’t add the scripts again, despite them being in the proper directory and viewable in both the project folder and in the file explorer. If I drag a script onto an object I get the following error message “Can’t add script component because the script class cannot be found.” None of the scripts have been edited.

Anyone had this problem yet? I’ve never had this issue before, so I can only assume it has something to do with Unity 2017.1.0f3.

Have you tried deleting the Library folder after exiting Unity? Sometimes allowing Unity to rebuild this folder will resolve odd issues like this. Otherwise, restore from backup and try again.