If computer work in safe mode but black screen on normal mode then what reason behind of this situation?

There might be issue with your Operating System also, either it is pirated. Or better to check the Display Drivers first.

If your cursor is blinking on top left side with black screen then most probably its display driver issue. If your computer stop working with any driver issues then using the option "last known good configuration" at startup would solve the problem

Operating System is effected. Its might be missing boot sector or NTDLR missing. Please repair your OS or re-install.

I would suggest you to look at your display drivers try to un-install or delete the display drivers in the device manager or try to change the screen resolution from the display settings. I hope it should solve your problem.

the main problem is Random Access Memmory properly not working 

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