Changing between 32 bit and 64 bit Windows 7

I have the 64 bit version of Windows 7 and one of my programs will only run on the 32 bit version. Is there a way to change to 32 bit. I do not have the software and it came pre-loaded on my laptop. Thanks in advance for your response.

Not without acquiring a disc with the 32-bit edition on it and installing from scratch. Most programs work just fine in a 64-bit environment, though. What is the program called?