One of my friend asked me about this problem,  it will boot to bios but will not recognize bootable device in his HP laptop.
I had that problem in my Thinkpad R40E so I suggested him to change the boot from Cd and once the new operating system loaded change back to hard drive as bootable device.  He did it , still it does not recognize.  Is it possible due to corrupt hard drive or even re-downloading bios did not help?
Is this the symtom of motherboard sickness? Any suggestion !!!!!!!!!!!

http://www.techsupportforum.com/hardware-support/motherboards-bios-cpu/224506-computer-wont-recognize-any-bootable-devices-unable-access-bios.html

Thanks, Any suggestion should be like teaching to preschooler. If possible step by step instruction.

Is the thumb drive (flash drive) still in the USB drive? If so remove it and try booting again.

This may occour if you had upgraded from XP to vista or windows 7.

Since you are able to get to BIOS ( again being very vague, as settings differ)

Go to settings where it says Peripherals, or Find your hard drive. Try and change it to SATA, or Legacy...basically Just toggle with the available settings under your Hard drive.

I'm pretty sure this will work. I had this problem also a while back.

Thanks to all, it was motherboard and now the computer is piece of sh**t.