I have a sony vaio, that up until a few weeks ago worked fine. I made some recovery discs and since then it won't boot up, I get a message saying boot manager not found, so tried to recover through the bios and a message tells me operating system not found. I have no original discs with it. Can anyone help me with this ?

Did you successfullly make "recovery disks"? If you did, have you tried to boot from those disks? You may have to get into the BIOS and change the boot order (DVD first).

I doubt that making recovery disks trashed your hard drive (but one never knows). Make sure you didn't screw something up in the BIOS. Make sure the hard drive is properly inserted. You could unscrew the cover over the hard drive, remove the hard drive and reinsert it. This will make sure that you have good contact between the pins and receptacle.

Reinstall

Go into the bios and set everything back to default and then try it. You may have a corrupted hard disk, you could just try a repair with your restore disks.