Hello Thibertk and welcome to Seven Forums.
Did you format the entire hard drive or just the C: partition containing the operating system? If just the C: partition you may still have the hidden recovery partition available. Does your Vaio have an ASSIST button just above and to the right of the keyboard ? If yes, while your computer is off, press the ASSIST button to launch Vaio Care Rescue. Click Start Recovery Wizard. Select Tools and then select Start Advanced Recovery Wizard. Follow the prompts to restore to factory specs.
If you don't have an ASSIST button, start the computer and immediately start clicking the F10 key (top row of keyboard.) If the recovery partition is available you should see a screen called Edit Boot Options. Click the Enter key and select Start Recovery Wizard and follow the steps as above.
But if you don't have a recovery partition available I would forget about trying to do a recovery to factory specs. Even if you found someone with the exact same model Vaio, it's very possible that their computer has a different hard drive or a different motherboard and their recovery disks probably wouldn't work on your machine.
I would do a clean install and follow the instructions in this tutorial. There's a special note for Vaio owners at the bottom. And if you need an official Windows 7 installation disk (which contains many of the drivers
your computer will need), Step # 1 has a link to an official Microsoft download site. Find the ISO of the Windows 7 version that originally came with your Vaio and download it to your desktop. Then burn it to a blank DVD. And make sure you have your 25-digit Product Key available because you will have to reactivate with Microsoft. The Product Key is either on the bottom of the Vaio or under the battery in the battery compartment. Clean Reinstall - Factory OEM Windows 7