Missing song and video purchases

I have been an Apple customer since 2003. I have purchased over 1,100 songs and approximately 30 music videos from Apple in iTunes. Currently, my purchased music in iTunes shows that I own only 250 purchased songs and 5 music videos.

I have purchased songs and videos, but they are nowhere to be found. I have also been an Apple Music subscriber since 2015. Please advise how I can retrieve my purchased songs, which were $.99 apiece back in the iPod days, and my music videos, which were $1.99 and $2.99.

Thank you,

Greg