itunes library doesn't match itunes media music folder. this is on a windows 10 pc and everything is up to date.

You don't synchronise your iTunes Library with the iTunes Media folder.

Your iTunes Library lists music that you have added (not synchronised) to the library. Some, but not all, songs listed in the library will be in the iTunes Media folder. So the number of items in the folder is unlikely to be the same as the number of songs in your library.

• • If the folder has fewer songs than the library, the remainder of the songs will be in other folders
  • If the folder has more songs than the library, it may (note "may") be because not all the songs in the folder have been added to the library, in which case, you can add those additional songs by using File/Add file to Library

Don't forget though, that there may be other files in the iTunes Media folder, such as artwork and compressed files, which are not used by iTunes. (The artwork is usually inside the audio file, but purchased songs often have a file for the artwork in the folder as well.)

What exactly is your concern?

If they matched until recently see Empty/corrupt iTunes library after upgrade/crash - Apple Community.

Otherwise you likely need to import the media folder, and then remove any dead tracks.

See Duplicate songs in iTunes - Apple Community if the import creates duplicates and KillDeadTracks if you have broken references to files you've deleted.

tt2