It is neccarily generic in the hope that you, or anyone else, might find all the information they need to successfully transfer their library from one computer to another. If you'd like me to go into specifics please provide some more detail on what you have done so far. The core of an iTunes library is the .itl database which had entries for each item in the library and notes where they are stored. If the library that you've restored doesn't have the expected content then perhaps you were using a library file on a different path before you upgraded the computer. The Previous iTunes Libraries folder is one that people sometimes have used when trying to recover their library at some earlier point in time responding to another incident. See also Empty/corrupt iTunes library after upgrade/crash - Apple Community which is linked to in the other document.
You note that files are hidden in Windows Explorer. I take it you've checked that they still exist and haven't been removed? See Repair security permissions for iTunes for Windows - Apple Community. You should be able to unhide all of the content of your media folder and ensure that your user account has suitable read & write permissions.
While you should be able to reimport any locally stored content that doesn't restore play counts, playlists, date added etc. Hopefully your backup contains a more up to date version of your .itl file somewhere. I note you've used the word import in your original post. When transferring a library nothing should be imported. You either copy the .itl file into the standard location of <User's Music>\iTunes before installing iTunes, or press and hold down shift as you launch iTunes to choose the .itl file wherever you have decided that it should be stored. All content comes over, ratings, play counts, playlists, date added, etc. In some cases (where the library wasn't portable and hasn't been copied to exactly the same path) iTunes may complain that it cannot find the item that you want to play, but it should all be listed, and there are ways of fixing that issue should it arise.
tt2
