Good day classic35mm, thanks for your question. I am glad to be able to provide assistance to you today. To do a backup of the registry, press Windows key + R and then on the run box type in there regedit and press Enter or hit OK and when the Registry Editor opens click File > Export > Select the location of the registry save file > click Save and to restore it from your saved registry file, locate the file that you have saved and then right click on it and click Merge and a confirmation message will appear and then click Yes and this should restore the registry and another way to do it is via the Registry Editor and then go to File > Import and locate the file that you have saved and click Open to restore it from there.
Regards,
Paul R.