Hey missblondie2013! Welcome to the community!
Spotify would love to have all artists and songs available there are, but sometimes agreements can’t be reached with the artist or label or a change may happen in music ownership.
There are thousands of albums and artists added to Spotify every day. If you can’t find a song you’re looking for, they may appear soon! You can read more about requesting music on this page!
Have a nice day and keep rocking! :)