As to reinstalling, I no longer ask folk to install Windows. Use the restore media. Install Windows from scratch is asking a lot of folk today. How to use the restore media is documented at the web pages about your model up at HP.com
About the HDD, a 500GB drive is under 40 bucks on Amazon. It's not hard to change. There are youtubes about changing it if you never did this before.
My screen says my hard drive failed. Do I need to buy a new one or can I try re installing windows 7? If so, how do I reinstall it?

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