Let's start with: [v57+] Places Maintenance is built into Firefox.

Type about:support<enter> in the address bar.

You will find Places Database near the bottom. Press the Verify Integrity button.

When done, copy and post the results here.

> Task: checkIntegrity - Unable to check favicons.sqlite integrity: Error: Error(s) encountered during statement execution: database disk image is malformed > Task: invalidateCaches - The task queue was cleared by an error in another task. > Task: checkCoherence - The task queue was cleared by an error in another task. > Task: expire - The task queue was cleared by an error in another task. > Task: originFrecencyStats - The task queue was cleared by an error in another task. > Task: vacuum - The task queue was cleared by an error in another task. > Task: stats - The task queue was cleared by an error in another task. > Task: _refreshUI - The task queue was cleared by an error in another task.

The places.sqlite file contains your History and Bookmarks. And it looks like it is corrupted.

Type about:support<enter> in the address bar.

Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

Locate the above file. Then rename or delete it. Restart Firefox. The browser should then create a new place.sqlite and recover your bookmarks from the backup files. Note: Your history is not backed up and will be lost.

the bookmarks are gine from browser?I don't have create any backup

Also are two folders with the ending default

Firefox automatically makes backups of the bookmarks. These are stored in the bookmarkbackups folder

i attach a screenshot.which of them must rename?

Those are the profiles in your user account. Do Not Delete.

which folder wil need to rename or delete ?I am confused.I follow your instructions.These folders appeared

Re-read: https://support.mozilla.org/en-US/questions/1279923#answer-1290519