Try hitting F1/F2/F10 when the system is starting up. Use this to enter the System's BIOS setup. Find an area called Boot Order or Boor Priority. Be sure that HDD/Hard Drive/Hard Disk is selected before LAN/Network. If this does not solve it, it means that your computer has failed to boot from the HDD, CD, and FDD (if there). As far as "Operating System Not Found", that means that you have formatted partition on your hard drive with no bootable operating system or you have a bad Master Boot Record (MBR). Reinstalling Windows or whatever your OS is should solve that.
There is the possibility that you have a bad motherboard. If so, you are indeed better off getting another laptop. If you are willing to pay and open up your machine, the motheboard can most likely be found at
www.impactcomputers.com
-Eddie