Hello Mehrshad,
Welcome to Microsoft Community.
Honestly, it's hard for me to tell what's going on just from your description of the problem. Maybe the system is stuck? Or is there a bug?
What you're mentioning here is that the taskbar is locked? If the mouse click does not respond, can you press the Windows key on the keyboard to open the Start menu?
In this case, if you can't even right-click on the taskbar to open the task Manager, use the key combination Ctrl+Shift+Esc to open the task Manager directly, locate Windows Explorer (the icon is a folder), select it, and click "Restart". The taskbar should then reload. Check to see if the taskbar is back to normal.
Best Regards,
Mitchell | Microsoft Community Support Specialist