How can I recover Macintosh HD and Data Volume after accidental deletion?

I was simply trying to do a factory reset on my laptop when I found myself erasing Macintosh HD and Data Volume off of my laptop. When I select either one it says "Not Mounted". Every time I try to restore it asks for an image but there are no images to choose from. I want to get these back so I can download the OS and use my laptop. Any suggestions?

[Re-Titled by Moderator]