A THREAD FOR NEWCOMERS!

I have Heroes of Might and Magic, I play without any glitches, but now it turns out that The Shadow of Death doesn't open? I installed The Shadow of Death on Heroes of Might and Magic, and before everything was fine, all maps from the internet opened perfectly. Now, not only is there this problem, but I also can't generate maps myself; it gives an error, and it doesn't even start, an error message pops up. I can't reinstall The Shadow of Death; it automatically installs to drive D, in the Programs folder, and there's a mess there – it's hard to tell what belongs to Heroes of Might and Magic and what doesn't. It's a real mess.