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Thank you for posting on HP Forums, MKazi is at your service.
I understand that you have an HP Pavillion x360 Convertible 14-ba0xx series laptop. I read that while typing the wifi password, only the letter P does not type/register. However, the letter P works fine every where else. I'll be glad to assist you with this case.
The evidence indicates that the keyboard should be fine as the letter P types everywhere else. I suggest you to check with external keyboard (if available) if you're able to type the letter P for the wifi password.
Another option is to use the "on-screen keyboard" in Windows. You may type "on-screen keyboard" in the Windows search and it should populate. Please click on it and to launch the on screen keyboard.
Hope this helps. Feel free to keep me posted about the results.
All the best! 🙂