Why doesn't Android studio display sources correctly?

Question

gradle

One fine day I open the project in Android Studio 3.4, and there the R class was not generated. Well, I think it happens. I 've tried Clean Project, Rebuild Project, Sync Project with Gradle Files, Sync with File System, Invalidate Caches and Restart but they don't help. As well as manually deleting the .idea and build folders .
Then I got into AndroidManifest.xml , and there was some kind of mess - instead of the manifest, pieces from gradle.build , and in gradle.build pieces of code from auto-generation files ... To my horror, I found out that in the source codes in the middle of the code there are also pieces of code from gradlefiles. The horror left when I looked at the source codes through a notepad - everything is clean and in place there.
It became very interesting what happened to the Studio, and how to fix it?

Answer 1

Everything turned out to be quite simple: you need to delete the folder C:\Users\my_user_name\.AndroidStudio3.4\system\caches

Answer 2

With hard drive. With RAM.
The described symptoms are a serious illness of the computer.