My friend is having a saudi assembled computer and he was using two operating systems Win XP and WIn98 but suddenly one day he loss his both operating systems. When he click on xp it says, some technical error has occur or may be the new hardware is plug something like that he is telling. I thought that may be the files got corrupted and its has to format. But when I restart the system it is not showing the options like DEL to entire setup nothing , and also the configuration from F8 is notworking.

Try pressing F2 at boot to enter the BIOS. Many older Dells use F2 to enter the boot options screen. From there you should be able to set which drive to boot from in the boot options screen.