Hi Soraya918, could you describe this problem in more detail? What do you see that is blocking you from using your computer or your Firefox normally?

The following is for Windows or Mac:

If Firefox diverts to an unwanted page at startup, or during browsing, could you test in Firefox's Safe Mode? In Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the Shift key when starting Firefox. On Mac, hold down the option key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement?

Do you get your normal home page in a new window (Ctrl+n; Mac: Cmd+n)?

(More info: Diagnose Firefox issues using Troubleshoot Mode)

Or if Firefox takes up the whole screen and blocks the Windows Taskbar or the Mac top menu bar, you can try getting out of full screen as follows:

• Windows: F11 key
• Mac: Command+Shift+F

Or slide the mouse pointer up to the top of the screen and watch for Firefox's toolbar area to slide down. This may take a couple of tries. Then either:

• click the "3-bar" menu button and click the Full Screen button
• right-click (Mac: Ctrl+click) a blank area of the title/tab bar and look for Exit Full Screen Mode on the short context menu

If a window doesn't offer those options, you can try closing it using either:

• Windows: Ctrl+w
• Mac: Command+w

Any luck?