My dell desk top does not boot. plz help.

Hello,

my computer suddenly does not boot. when i turned it on, i had a black screen with the message "strike f1 to boot." when i strike f1, it makes a beep sound and ask me to strike f1 again.

after i tried again and again with failure, i tried to reinstall the xp, then it said that hard drive could not be found.

is this hard drive failure or processor failure or something else?

thanks for any suggestions