System not working

[nikkytyagi74]

Hello, Please help....suddenly, my computer shut down. It will not boot. Does not respond t F8...only allows me F2 and F12 options. I get a cursor on the upper left hand side of the screen. It is white and blinking.

 

[CountMike]

That flashing white cursor means that your operating system is corrupted and can't boot into it from disk.

 

[SkyNetRising]

It can be multitude of things:

• faulty hdd,
  corrupted bootloader,
  corrupted OS,
  incompatible boot mode settings in BIOS,
  ...

Start by checking BIOS settings.
If those are fine, proceed to diagnosing your HDD.
If it is fine, then proceed to file system checks, bootloader checks and possibly to reinstallation of OS.