Google Keep, the company's note-taking app, is getting a long-overdue feature that unfortunately doesn't seem fully baked. Google is adding a version history function, which could save you from having to manually retype a lot of text that you mistakenly deleted.
The tool allows you to download a text file with previous versions of your notes and lists, according to a support page. The help document states that Google is gradually rolling out the feature to everyone, so it may not be live for you yet. When it is, you can access it on the Keep web app, by clicking on the three-dot menu at the bottom of a note.