Right click on a tab and check it out..

Use CTRL + SHIFT + T > Undo closed Tab

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).

To Enable SafeMode

• You can open Firefox 4.0+ in Safe Mode by holding the Shift key when you open the Firefox desktop or Start menu shortcut.
• Or open the Help menu and click on the Restart with Add-ons Disabled... menu item while Firefox is running.
• Once you get the pop-up, just select "'Start in Safe Mode"

don't work http://ww1.hol.es/up/4a93f0332b25.jpg

Hello,

The Reset Firefox feature can fix many issues by restoring Firefox to its factory default state while saving your essential information. Note: This will cause you to lose any Extensions, Open websites, and some Preferences.

To Reset Firefox do the following:

1. Go to Firefox > Help > Troubleshooting Information.
2. Click the "Reset Firefox" button.
3. Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish.
4. Firefox will open with all factory defaults applied.

Further information can be found in the Refresh Firefox - reset add-ons and settings article.

Did this fix your problems? Please report back to us!

Thank you.

You can check these prefs on the about:config page:

• browser.sessionstore.max_tabs_undo
• browser.sessionstore.max_windows_undo

• http://kb.mozillazine.org/about:config

Hello cor-el Thank You, Thank You it's Work

Try this add-on

Undo Closed Tabs Button

You can check these prefs on the about:config page:

1. Typed In about:config in url 2. Checked for following preferences. 3. Set value accordingly:

browser.sessionstore.max_tabs_undo SET VALUE to 1 browser.sessionstore.max_windows_undo SET VALUE to 1