This article will help you fix problems caused by a corrupt localstore.rdf file, which include:
- Changes to the toolbar reset themselves after you close Firefox and start it up again
- Window size or position not remembered at startup
- Bookmarks appear in the Bookmarks Manager but not in the main menu and can't be edited 
- "Add Bookmark" dialog not working 
- Back/forward toolbar buttons missing after Firefox upgrade and unable to restore using "View -> Toolbars -> Customize" 
- Navigation Toolbar (a.k.a Location bar, address bar) or Bookmarks Toolbar is empty, even though selected in "View -> Toolbars" (or in Firefox 4 Options sub-menu). 
- Unable to save or download files because the dialog box prompting you to open or save a file does not appear. 
If you have a backup copy of the localstore.rdf file from a working Firefox profile, a quick remedy is closing Firefox and overwriting the localstore.rdf file in the Firefox profile folder with your backup copy.  If you have no backup, you need to remove the localstore.rdf file and let Firefox generate a new copy. Your toolbar customizations will be gone when you next restart Firefox but future changes will be retained.
Before continuing you may wish to save a screenshot of your Firefox toolbar customizations, to help you restore them later.
Note: You can restore the default set of toolbar items from within Firefox by opening the Customize Toolbar dialog ("View -> Toolbars -> Customize") and selecting "Restore Default Set" but this does not restore the default content of the localstore.rdf file and is not a solution if the localstore.rdf file is indeed corrupt.
Use either of the two methods given below, to regenerate the localstore.rdf file.
Safe Mode method
Restart in Firefox Safe Mode using the instructions in the Safe Mode article. After restarting, a window called Firefox Safe Mode with some troubleshooting options will appear:
Select the option "Reset toolbars and controls" and click "Make Changes and Restart".
Caution: Do not delete the localstore.rdf file in the Firefox program installation folder by mistake .
- Back and forward or other toolbar items are missing at support.mozilla.org
Related bug reports
- Bug 99236 – localstore.rdf should be deleted when it is corrupt (fixed in Firefox 220.127.116.11)
- Bug 319196 – customized toolbar always reset to default on restart, bookmarks and search engines lost, unable to add search engines (localstore.rdf corruption on upgrade or crash)
- Bug 426026 – Back/forward buttons disappear when moving from 1.8 to 1.9 if they've been moved (Fixed in Firefox 3.0.2/18.104.22.168)