I am unable to access my Apple Music library on my PC

A little more information from you might help us to help you.

It's not clear what you mean by apple library, so to expand on what muguy has asked, do you mean the music listed in your iTunes Library, or the music files stored on your computer, or something else? Do you mean Apple Music (the subscription service)?

Or... have you installed the apps that replace iTunes and now can't see the music that you had in your library?

What library? iTunes? Where did you store your music, typically the library is in a music folder.