If the Vaio is new it probably has a version of Windows 7
There will be a label on the PC telling you what model the Vaio is
(Sony Vaio's often have 2 different model stickers to confuse you)
It would help if you knew if it was 32bit or 64 bit but most new PC's seem to use 64 bit Windows
You need to borrow a Windows 7 DVD .
Then read up (Google) on how to' fix corrupt boot manager windows 7'
The boot manager is usually located on a small hidden partition before your C: drive
so a restore point is unlikely to help
If all else fails recover any critical data before re installing from recovery system
The recovery system can return the Windows to 'as delivered' state
The user guide telling you how to do this will be on Sony's support site (and probably on your C: drive)