Windows 7: boot up problems windows 7 - on operating system

brothers laptop samsung np-r519

tried to boot up but it is saying no operating system dont have windows disc dont have recovery disc tried pressing f4 on boot up but it says boot from ACHI .
pressed f2 and sata 1 is recognised i think .

any help much appreciated

Hi and welcome to Seven Forums!

Your problems are with Windows XP or Windows 7? In your System Specs there is xp...

My laptop has xp , the problem is with my brothers laptop his runs windows 7

Have you or your brother recently made any changes to the BIOS? Did you recently install a program in Windows?

Not that he is aware of but he ain't the brightest when it comes to pcs

Make sure the Windows 7 HD is set as first HD to boot in BIOS setup.

Then check the SATA controller settings as it may have been changed from IDE to AHCI. Try all settings.

If these fail then reset BIOS to defaults to try again: Clear CMOS - 3 Ways to Clear the CMOS - Reset BIOS

If these all fail then work through these steps for Troubleshooting Windows 7 Failure to Boot which lead up to possible rescue of files if necessary, then running Samsung Recovery or Clean Reinstall - Factory OEM Windows 7 - the latest official installer needed for repairs or reinstall is in Steps 1 and 2.