Is it turned on in Windows? Go to Control Panel> Programs and Features> Turn Windows Features on or off>Tablet PC Optional Components. Even if it's ticked, maybe you could try unticking and reticking it and then a re-boot. It's worth checking at least.
I don't know what you have tried, but hp.com has all the drivers for your laptop. Go to hp.com click on the support and drivers tab, then click the Download drivers and software (and firmware). Then type in the make and model of your laptop, be as specific as possible. If you don't type in the exact name you will get a list of possible computer models, then you click on your computer model. Then click your operating system this will bring you to a download page which will contain all of the drivers and software available for your computer, including the touchscreen driver.