proguard-project.txt not found in android studio

Use the proguard-rules.txt file instead. Proguard doesn't attach any special significance to the name of its rule input files; it uses whatever's set up in your build files, which for new projects created in recent versions of Android Studio, is:

buildTypes {
     release {
         runProguard false
         proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
     }
 }

The proguard-android.txt file lives inside your SDK, and contains reasonable Android-wide defaults that all projects should use.

You can find proguard-project.txt in

C:\Users\"USER"\AppData\Local\Android\android-studio\sdk\tools\proguard

"USER" is the name in you will see when you click on c-drive \users \yourname

I had the same problem when I started using Android Studio

You can't see the ProGuard files because you are previewing you project in a non Project file mode. Which most probably will be Android view mode.

You have to change the mode by clicking on the drop down list of the Android selection and select Project Files to see all the files in the project as the following:

Then you will be able to see the hidden files in the Android project structure view mode.

And here is a good example for the ProGuard