How do I recover deleted Registry entries if I did not do a back-up restore point earlier?

while trying to delete some entries clean up a virus, I have accidentally deleted some entries that read something like %SystemRoot%\dll…..

After that, I am unable to download emails into my Outlook.

Is there anyway I can recover the deleted entries (which I cannot remember the path or value+data) without having to reformat my entire OS?

Thank you.