|"..a drop of water in the corner of screen fell."|
A liquid spill, or dropping a laptop, are the most common causes of a laptop getting seriously damaged.
When you spill liquid on a laptop, you should immediately disconnect the AC Adapter and unplug the main battery to greatly lessen the chances of it being damaged, wipe up the liquid, and if you're not sure whether the liquid got inside of it, you open up (or you have somone else open up) whatever you spilled the liquid on, the screen or the base, or both, and wipe up all liquid found. It doesn't matter whether the laptop was running when you spilled liquid on it, it could still be damaged - the atx mboard is always powered in some places as long as the main battery is installed.
The HP web site has free Service manuals available for examining online or downloading for most laptop models, if you want to try opening up the display or the laptop base or both yourself.
Laptop no video and battery / AC adapter / laptop power jack T shooting
See response 1:
If you get no display when you connect a external monitor, see the Owner's or User's manual for your model. Some laptops have a key or key combo you must press to toggle built in display / external display / (sometimes) both.