This has NO research or looking-up involved, it is strictly from memory, so i may be off on a bit:
First of all is it a notebook or a desktop? (too lazy to google the title
)
(MOST LIKELY!!)Would you happen to have XP/Vista/Me/2000/3.1's
(jk) install disk? just pop it in and either do a system repair or reinstall the OS withought deleting files...
The Hard drive could have just DIED...
The Hard Drive could be disconnected (but i dobut it unless you ever took the cover of the PC off)
Corrupted Boot.Ini file... but that is probably the least likely because it shows a different error... and i cant be 100% sure unless you describe your problem in explicit detail. and if it ever is you will need to disconnect the hd and all this that im not going to explain untill im sure it is this...
(second most likely, but i cant give detail unless i have the PC infront of me) Your computer got a virus... there are some that can, once your PC is off it cant reboot... But first do you get past the WIN XP loading screen with the bar? If you do read the next paragraph... if you dont skip it
In the loading screen press F5 (maybe F7) to go into safe mode and try to disable/remove the virus.
Otherwise your S-O-L buy a new PC.
Glad i could help
,
~Simitra