make software 64bit compatible.

Hello, I have a source code of a little program, problem is it only works on 32bit systems, I need it to be rebranded, but also that it works on 64bit systems. The rebranding was doen before, but we lost the sourcefiles for it, but we do allreayd have compiled version. So one can use it to see what needs to be changed. Its very basic program just a few places changing the name and logo and references. About making it 64bit compatible, I dont know how easy and fats one can do it. Anyone who wnats to give it a shot let me know, Its C++ language. Cheers,