HP ENVY 700T will not boot up

I have an HP ENVY 700t computer running on Windows 7 with a 400GB HDD. The computer crashed all of a sudden while I'm on the internet. When I rebooted it, it will no longer boot to Windows. I reinstalled the OS and it didn't resolve the issue. How should I know if the hard drive is failing. Is there a certain diagnostic I can run?
