Hello thewall58,

You can try to search the executable file (.exe) for QuickBooks 2001 in your drive (C or D), and use it to reinstall the program. Once you're able to do it, you'll need to register the program again as what being mentioned by @Rustler. 

If you can't see this executable file, we don't have other options for you but to upgrade. 

We'll be right here to help if you have any questions.