No Bootable Devices: Strike F1 to Try to Reboot, F2 for Setup Utility

If you press F1, the computer reboots back to the same message and F2 will take you the BIOS setup screen.  If you do go into the BIOS, check and see if the system is seeing your hard drive under the IDE or SATA device screen.  If the hard drive is seen here then Windows is likely corrupted.  However if the drive is not in the list, then there are only a few other options.  First, check for any loose cables inside the computer (assuming desktop.)  Replacing the cables may fix the problem.  The other option is that the hard drive is dead or the motherboard is failing.  Hooking up the hard drive to another computer will determine this.  If the hard drive is dead, getting your data back may prove challenging.  If the operating system is corrupted, getting the data back could be as easy as hooking it up to another computer and copying the data over from it.

Simple Answers:

 •  Software Failure:  Reinstall the operating system.

•  Hardware:  Time to buy a new hard drive.  May need to send the drive to a professional for data recovery.