my ADVENT laptop was working fine and then shut down it wont start up again, I get the ADVENT screen and the options F2 F8 and F12 but when i select any of them it just goes off and on again repeating the same performance... can anyone help

Do you hear your HDD spinning?
Try going into bios and see if you HDD is shown properly.

Your hard disk might have crashed. Check whether your hard disk is working correctly. Take the hard disk out and test it on another laptop, if it fails that mean your hard disk need to be replaced. Is you battery low, try charging your battery before starting up again. Make sure all your components are place it tightly and correctly.