HP Pavilion zt1122s notebook

Please can anyone help
I am losing the use of the G H @ and backspace keys . Additionally the L button is upside down.
To get around it I am using a usb keyboard.
This happens occasionally altjough of late it seems more frequent. i tend to change the sticky key setting and reboot and it comes back sometimes. The keys arent stuck and when working they do so fine

help!!!!