If I back up some or all of my installed program files and then maybe have to replace a corrupted install at a later date, does the backed up files also have the registry files needed to work the returned program or just the files in the program folder.
Obviously not! If you backup program files it will contain just that, the software files. The registry is not affected in any way. That said, the vast majority of programs do NOT require anything special to run and copying the program files folder will do in 99% of cases, but that's not the way to do that.
What you must do instead is to backup the installers. Forget about everything in program files, the registry or anything else. If you have the installers and your system crashes and need to reformat, simply pull your backups and reinstall everything as it was previously, and those installers will take care of putting all dependencies in place as they were before.
Of course, and most important, you need to backup your data too.
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