Unlike most other Google/Chrome things, your browser bookmarks are relatively vulnerable in the sense that there's no revision history, no "undo" if you accidentally delete one, etc. If you have a lot of bookmarks that matter, here is how to make a backup copy (this is within the Chrome browser):
1. On a Mac: Go to the Bookmarks menu and select Bookmark Manager
On Windows: Go to the three dots in the upper right, then to Bookmarks, then select Bookmark Manager
2. Click the tiny three dots in the upper right hand (blue bar) of the screen and select "Export bookmarks"
3. Save the resulting file somewhere convenient
4. For bonus points, upload the file to your Google Drive!
Here's a short screencast demonstrating these steps (no sound):
https://www.youtube.com/watch?v=L0EM-2106vA
Now, if you accidentally delete them, you can IMport the backup file to restore them.