Registry Merge

I managed to corrupt my system registry and was wondering if the CCleaner Registry Merge might correct that. Several questions:

1. What do the CCleaner registry back ups contain? Is it the complete registry or just what was deleted?

2. Is there a way to merge this file to the corrupted registry in hopes that it will fix the corruption?

Since the drive that I need to restore the registry on is not bootable I need to boot from another drive or attach it to another system. I can get to the CCleaner registry back ups but when I select Merge it does not tell me where it will merge to, nor does it give me the option to select where I want it to merge to.

I have tried rolling back to the last good installation but unfortunately those files appear to be corrupt and I can't use them.

Ccleaner backups contain the reg entries of what was deleted at the time you made the backup.

How did you corrupt the registry?