The screen of my sony vaio disappear when i open

if you reformat the drive then you will need an operating system to put back on ... but you likely dont need to do that ... since you can open it in safe mode then you probably have a driver messed up on the hard drive ... in safe mode you can do a system restore .. this will set your system back to the state it was in before the problem happened .. thats
start, all programs, accessories, system tools, system restore (may vary depending on your operating system) .. if restore doesnt work then you should reload your drivers .. like video, sound , motherboard and such .. those are likely available for download from sony .. .. there are lots of things you should try first .. reformat as a last resort .. once you get the thing going then you might be able to make a systems disk .. instead of giving you a DVD with windows on it, they often provide that system hidden on your hard drive ... you can sometimes make your own recovery disk from that ... if you had a windows disk for your machine then you could repair your system with that without having to format .. .. sometimes there is a special key combination that will restore you system to its original state .. but you might loose everything in doing that unless things are backed up ... in fact since you are able to use safe mode then it would be a good idea to get a jump drive and put anything important on that while you can ..