How to find entry in registry of an uninstalled program?

I want to know how one can find th开发者_开发问答e entries in the registry of an uninstalled software. Can someone help me out because I have no idea?

If you scan through the registry, some of the keys will point to files on the disk. If these files do not exist, that is probably a key for uninstalled software. Any key that references this key, is also probably for uninstalled software.

You can't. The registry does not store the "source" or "use" of a registry key.