Hp compaq cannot boot from a cd why?

Check your BIOS boot settings. If you want to boot from a CD, you need to tell the BIOS to boot of the CD 1st and then Hard drive, etc, etc.

If you can't boot of ANYTHING, then we need more information, any erros, whaty is displayed on the screen?
 
i tried to flash the bios .. i did it and then nothing same problem. but then i take off the cd rom material and boot from usb cd rom and it pass !!! everuthing is fine. the read error was caused by the cd rom material and i had to buy a new one i guess... i hope this will help others ..