Welcome to HP Support Forums. 🙂 I came across you post and would like to help. I read that you have an HP Envy x360 2 in 1 laptop and when you try to use it in tablet mode, the keyboard does not get locked up and due to this the laptop pressed keys in tablet mode.Secondly, the sound volume is low.
I recommend you to perform the below steps to isolate the issue and arrive at a solution:
Power off the laptop.
Disconnected AC adapter from the laptop.
Press and hold the power button for 15 seconds.
Reconnect the AC adapter.
Power ON the laptop.
Please check the sound output and if the sound is low then I suggest you to perform the steps from this link. These solutions are explained in detail in this document: http://hp.care/2hWQ9sW.