How do I restore an earlier version of a file?

Right-click the file in Files and choose Version history. In Docs and Spreadsheets it is also under File → Version history

There you can:

• Look at any earlier version and see what changed
• Restore it. The current content stays in the history, so nothing is lost
• Name this version to find it easily later
• Download or delete a version

An old version is kept for 30 days after it was replaced, and each version shows how many days are left. Versions made close together are merged over time