Just a few suggestions:
1: If RootsMagic is on the START menu, try starting it from there.
2: If it's not there, try to find it in My Computer (usually the folder is C:\Program Files\RootsMagic 4) and double-click on the RootsMagic.exe file.
3: If the RootsMagic.exe file is not found or will not start, you may need to re-install RootsMagic.
On the brighter side, the data files should be safe as they are stored separately from the program files.
Hope you get things sorted out.
Mike.
Oh, and I suppose you have tried turning it off and on again

(this does actually work sometimes)