Q: What happened to my itunes library?

I've had an iTunes account for so long, too long to remember. I've spent probably thousands of dollars on music downloads over the years. I buy iPhones with more memory so I can keep every single song on my phone, because one never knows what type of genre they want to listen to any one day....

Somehow, all of a sudden, I noticed I only have about 250 songs. Considering I just mentioned I've spent thousands on music, clearly, 250 songs is not right. But I can't find the music anywhere.

I found instructions on how to unhide something you've purchased, music, books, movies, etc. That didn't work. I had one song in there, which I just accidentally put there today, so at least now I have that back....

Has this happened to anyone else? Does anyone know how to retrieve my old library?

TIA!!!