Hello FathullahNaimzai,
I'm John an Independent Advisor and a Microsoft user like you. I'll be happy to assist you today. I understand you have a problem with Pashto Afghanistan Keyboard Layout is not showing in the language list.
Please try the method below if it helps.
Press Start then click Settings(Gear icon) > Time and Language > Language
First you need to add Pashto (Pakistan) under Preferred Languages
After that, select Pashto (Pakistan)
Select "Options"
Under Keyboards > Add a keyboard
Select Pashto (Afghanistan)
Select Arabic then click remove if you want
Kindly check and test your Pashto (Afghanistan) keyboard layout
Kindly let me know if this helps or if you have any further concerns.
Sincerely,
John DeV
Independent Advisor