Operating system not found Sony Vaio

1. Staš •
POSSIBLE FIX: I've bought a new disk (ssd) and when I wanted to install OS I always got "OPERATING SYSTEM NOT FOUND". After that, I've googled tons of "press F(sth)+blahblah" tutorials and nothing worked for me. What DID WORK in the end was - making an USB bootable drive (using Windows USB DVD Download tool), then booting the machine using the ASSIST button -> BIOS -> then changed the Legacy boot to UEFI, went to the other tab and disabled Secure boot (which was previously grayed out) -> then switched back to Legacy boot. You also need to change the boot priority/sequence, putting the CD or USB in the first place. After installing (first restart) you'll have to move the disk back into 1st position/order. But that was it for me - works perfectly now. BTW my model num. is SVE1512e1ew. Good luck to all

2. Max •
Still wasn't able to work for me, my cd drive is making an odd sound while its trying to boot as if it's trying to access a cd. Any other things iIcould try?

3. tw1st3d •
Operating system not found meand that most likely your Hard Drive/SSD died and the computer can't find any data on it so it says it has no operating system.