When I try to open my Itunes Library, I get a pop up msg that I need to remove my current installation before continuing! Will this remove all my songs Playlists?

I'm so afraid to remove my current Itunes installation as I have approx. 15K songs- all have several playlists each. I certainly don't want to start over with giving each song Playlists! It would take me weeks to get thru all that! I've had my Itunes Library for probably 20 years. This is the first time it's requested me to do this! I've been putting this off for weeks - I'm now tired of being without my Music!! Please Help!