songs on my iphone but not on itunes on my pc

Thanks, but the great majority of the songs are not downloaded from the iTunes Store, but ones that I had ripped from CDs that I own (I checked and its well over 3600 songs). Also, I never did sign up for Apple Music (even though I had a free offer when I got my iPhone, probably should have done it), so that avenue is closed for me. I just wonder if there is a way to do a sort of "reverse sync" to get the songs back on the pc from my phone, maybe using an external SSD drive. I recall a similar (but not exactly the same) issue with my iTunes on my pc a few years ago. At that time, my entire library disappeared. I wish I could recall exactly how I resolved the issue, but I think I had to go back and find a version of iTunes somewhere in my C drive that was from a time prior to the disappearance and restore it from that. I can't imagine I am the only person this has ever happened to. Maybe I am not describing the issue well or something.

Thank you, this worked. I had to go through a couple of previous iTunes Libraries to find one that had the content that had disappeared, all the way back to 2019 (I guess that's when the update in question happened) but found one eventually. Anyhow, now I've got to redownload the songs I'd purchased from the iTunes Store since 2019* (not very many) and the albums I'd put on since then (quite a bit more) and then I should be all set. I'm bookmarking this page, though, since this'll probably happen again. Once again, thank you all.

*currently, the iTunes Store has no songs in my purchase history, but they all show up when I checked my Apple account, so I imagine it'll just take a bit for the purchased songs to show up for re-downloading.