I am not sure I follow your explanation of the problem.

Have you for instance set up groups of tabs that are in fact single windows of one open tab ?

That would display your windows as thumbnails when you click on the group icons icon.

By PM

hi John, i can not see, how many sites are open, because i do not see the tabs! i am sorry but i do not know how to explain it:( I see a window with my bookmarks -toolbar, menu bar and navigation bar, but no tabs for the sites, i am on! thank you for taking time and answering! 

What happens when you open a new tab for instance use Keyboard shortcut Ctrl +T does that open a new tab that you can see. Please attach a screenshot of your ordinary Firefox page e.g. open on this forum. And a screenshot of the Group Your tabs view.

• How do I create a screenshot of my problem?
• How to make screenshots

I could suggest trying the Firefox reset, but that may be rather premature

• Refresh Firefox - reset add-ons and settings

hi, this a screenshot of my fire fox, i have 3 sites open, but i do not see them, unless i press the "group your tabs" button!

and this is a "group your tabs" screenshot

It looks like they are individual Firefox Windows of a single tab. Obviously you have customised things. As I asked earlier what happens if you use Ctrl+T. Does that open a new tab in the current Window ?

You could use FirefoxReset, but that loses your customisations.

• Refresh Firefox - reset add-ons and settings

It would probably make more sense to create and use a new additional profile and consider the way forward from there. Preferably working on a copy of the profile rather than the original.

• Back up and restore information in Firefox profiles
• Profile Manager - Create, remove or switch Firefox profiles#w_creating-a-profile
• Restore bookmarks, passwords, and data from an old Firefox profile

The best method for a limited reset is probably to rename the profile's file named localstore.rdf. That will cause Firefox to create a new settings file with default options. Renaming the file gives you an option to reveres the change if necessary

• see http://kb.mozillazine.org/Corrupt_localstore.rdf

thank you so much john, i could not do it without your help! with your very helpful answers and links, i made a back up in fire fox profiles and with a new profile and etc.. could mange to restore all my setting ! thank you!!

Great, good to know it is sorted out. Thanks for posting back.