Hello @Mohammad reza jafari
Initially I would try to re-register the Taskbar and its components with the next Powershell cmdlet (from a Administrator window):
Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register “$($_.InstallLocation)\AppXManifest.xml”}
If that doesn't work, I would check if your computer may belong to an organization and they may have impossed some policies of which applications can be pinned.
In case the computer is not managed by an organization I think it would be helpful if you can share the steps to reproduce the issue and a screenshot of the taskbar.
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