so i have an hp pavilon notebook 15. was working great till windows updated to 8.1.then my hp support center (update drivers) stopped working.3 days ago my hard drive went down. i have an old hard drive from an asus laptop. the hp laptop is working but it wont boot up.on boot up it says i need to install an operating system. i have a flash drive with windows 7 on it and it wont boot from flash drive. i tried to burn it to discs and try it that way.didnt work. i downloaded win 8.1 and burned it to discs.that didnt work. i dont have the funds to buy an operating system.what can i do??