Hi christinegiummo, Sorry you are having problems.

Lets do all we can to ensure anything you do have is preserved. I do not want you to unnecessarily loose all your bookmarks.

First of all backup your bookmarks using all three of these methods.
(Unless you are absolutely certain there is no possibility there could be any bookmarks you may want.)

• Make a copy of the profile, this contains important bookmark related files.
  Back up and restore information in Firefox profiles
• Export the bookmarks as HTML
  (This type are easily examined, edited and used)
  Export Firefox bookmarks to an HTML file to back up or transfer bookmarks
• Export as Firefox backup files.
  Restore bookmarks from backup or move them to another computer_manual-backup

1. Repair attempt
   As a first try to fix the problem download and run the addon places maintenance. https://addons.mozilla.org/en-US/firefox/addon/places-maintenance/ You may wish to look at the report that it is capable of generating; before and after; you try the repair. This may repair the bookmarks so try the Library to see if it works.
2. Restore a Backup
   The second method will lose any bookmarks made in the last day Firefox was open. It imports an automatically created backup. It may work. CARE these restores overwrite existing bookmarks. always backup bookmarks before any restore is done.
   Restore bookmarks from backup or move them to another computer_restoring-from-backups
3. Regenerate a corrupt database File
   Warning This third method will destroy your History, so is the last resort.
   (You may be able to temporarily reinstate that from the faulty database) This relies on deleting the database file places.sqlite. Firefox recreates it using a bookmarks backup. There is no backup for the History and that is lost.
   • Find your Firefox profile, locate the File, places.sqlite and rename it (call it places.sqlite.old)
     Use FirefoxButton -> Troubleshooting Information -> Profile-> [open folder] button (or similar wording)
     See http://kb.mozillazine.org/Lost_bookmarks#Restoring_bookmarks_in_Firefox_3_and_above

You can check for problems with the places.sqlite database file in the Firefox profile folder.

• http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox
• https://support.mozilla.org/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file

Why should I have to save anything? This is nonsense for you to change the browser without warning and disrupt everything. Think I will just go to Safari instead

gwiger,

Bookmarks should not just disappear, that is a fault and you should try to follow the advice in my post above if you want to preserve them. We will then try to help you to get them back.

Or are you asking about a different fault where open tabs disappear. That was a known fault apparently that could occur on Firefox 29 initially, but is now fixed. (see)