If the screen stay black, it may be the screen that no longer work and need replacement. In this case, there will be some activity from the NumLock, CapLock and ScrollLock indicators and possibly some beeping.
The final state of the lights or some beep code will tell you what kind of problem you may have, several of witch mean that you effectively need to replace your laptop. With luck, it may be only mean that you need to replace your RAM.
If there is absolutely no activity, you have some other problem, like:
Faulty power switch or faulty power circuits. The first can be fixed, the second demand the replacement of the motherboard. Cheaper to replace the laptop.
Electro
July 2016
Does it do ANYTHING? Indicator lamps? Hard Disk activity? BIOS screen (The HP logo bit that happens before Windows starts).
XXX
July 2016
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