When I try to start up Roller coaster tycoon 2 I get a popup saying "please insert the disk into the following drive". If I hit Ok or cancel I get another popup saying "Missing or inaccessible data file" I'm not sure what's going on since the game was working yesterday.

I am having this trouble too. Is there a fix?

For me reinstalling the game worked. I did delete the entire folder though, so if you've been playing before, make sure to backup all your saves before you do that.