If you can't find a launcher you might have downloaded an iso. To refrain from a long tutorial, basically a CD is an image. When you install a program from a CD, user files are put on your computer, and then other files are read from the CD (that's why even after install you still need a CD to play the game)
Iso's take all of the files, user and system, from a CD and compile them. The problem? No launcher.
This is where you have to go find a program that will run the iso, like PowerIso.
Good Luck!