Laptop HP wont boot after hang up while working.

I recently recovered my laptop from BSOD with the help of this forum. Now a new problem came along when suddenly the screen black out, harddisk no response, as well as keyboad. Last option to restart is forced shut down. but after shuting down, i tried to start again, i wont start up.

all i can observed is that cpu fan is running, dvd rom turning, all lights in the keyboard lighted while numlock and capslock were blinking. i was suspecting that the Hard disc might be the problem since the indicator is not lighted or even blinking since from start up.

i'm planing to replace the hardisc but its better to ask for your advices rather to spend extra money..

just in case my hard drive is defective, how much it will cost me?

thanks!!

update:
i did your instructions. it didnt work out.
observations:
actually there is no first screen, screen all the way is black, there is no luminous indication of screen open up. it is like no boot sequence ever started when switch on.
i heard that dvd rom is running. but still nothing came up in the screen.
no hard disk reading indication.
all light lighted up while numlock ang capslock blinking.
keyboard no response.
last resort is to force shut down.

i'm in venezuela right now ang prices are expensive than US.

If you can't see the screen to boot then we can't really advise testing the HD and RAM. Likely mobo since you get no BIOS screen at all. Try Clear CMOS - 3 Ways to Clear the CMOS - Reset BIOS

ok!! that's great!! you're giving me a hopefull idea!!! i wish this will work and to enjoy web browsing. i remembered that, updated my bios from HP site. that may give reason why am i experiencing this.

another question: after i clear the CMOS, will my laptop CMOS be back to factory default. i choose to remove the battery coz, opening the laptop is difficult as i imagine. i might broke some parts and dont realy know which screw to be remove first. but then i remove the small covers, i found this blue like battery with wire:

i've done nothing so far from today, i just open up these covers that RAm, hardisk and that one with blue like battery.

i downloaded a bios upgrade from hp site, after i decided to install windows seven after the recent crash. originally it was windows vista 64bit home premium.

i removed the cmos battery, and put it back twice then started the laptop, but nothing happens. it stay the same as it was. i've seen in the you tube video that black screen is resulted from a micro chip melted solder. this might be the problem???

Did you try installing the BIOS update once you downloaded it? If so, did this problem happen afterward?

Are you sure it is for your exact make/model computer? Check again, using your Serial or Tag number if possible.

Read the instructions for installing the BIOS update if you haven't yet. Is there a way to install it from bootable media? Are the instructions clear enough that you feel you want to try it?

Have you considered seeking help with HP Tech SUpport who can RMA the mobo and/or walk you through trying the BIOS flash from boot?

in the HP site, i downloaded the drivers of my laptop according to its model and OS, then they will promt to you all drivers and softwares installed in that model and OS. then i run them, after installations everthing went fine, no more BSOD, i was able to use the laptop for 2 weeks, i think, then when i was about to run the video call for facebook, after a prompt to allow that program to run, i allow it then the black screen is next.

now the laptop is nothing and useless at all, since initial screen is never shown, (screen that shows HP logo). the screen remain black and no harddrive indication of reading even one blink.

i tried to insert bootable disc but it never run, nothing showed in the screen, even the keyboard no response. i can hear the DVD ROM is initiated as well as the processor fan is running.

i guese my laptop suffers GPU failure.