Hi, I am have had this laptop for 3 years now and suddenly yesterday it decided to die on me.

When starting up and getting to the VAIO screen it goes black screen and says "Operating system not found". Using either F10 and/or F8 to get to recovery mode doesnt work. Went to BIOS and reset to default but still get the same error.

Any suggestions??

Is HD being detected in BIOS?
If not, that would most likely be dead hard drive.

If you see it in BIOS, then it could be that the MBR or boot sector got corrupt. You should try to using XP Setup CD and use rcovery console there. From there may be able to remedy the situation by using FIXBOOT or FIXMBR commands, but that is a long shot..

Other choice would be burning ERD bootable image to CD and trying to fix the drive from there.

It's a Sony Vaio so it wouldn't have been supplied with a proper windows cd.

Nevertheless, it could help.

Undoubtedly! :) I was just pointing out that Sony are too cheap to actually supply a windows cd.

.. and they charge for replacement recovery disks.

"Customer supprot" means "supported by customers" there.

Absolutely! They are expensive to buy and even more expensive when they go wrong!