After formatting computer hard drive wit...

Hi there,
I have HP compaq desktop computer with windows xp pro. with partition. I had run out off space of the hard drive, so i decided to format the hard drive and do away with partitioning of the hard drive and also the change the format of the hard drive from Fat 32 to NTFS. Only way to chage that was to for mate it. after formatting and installtion of the windows xp it came up with error message of the bios and the floppy. It would not let me do anything so i had to turn the power off to the computer to over come the problem. Now it will not boot up nor the any of the drives open up. It keeps coming up and going off. (flashing effect). It does not give any time for the screen to come up. So please help how to over come this probem and thank you for your help.
your friend