look at the cd-key listed on the notebook you can either find a friend with that edition of windows or grab a disk online. Some sites list the download links to Microsofts digital river site. I won't post the link because I don't know what the policy for that is even though it is legal to install Win 7 for 30-120 days without a cd-key and the disks are true legal images. But if you use the links you just need to burn the disk using a dvd.
I don't understand what happened but you should REINSTALL the original OS that came with it.
If you have the ORIGINAL hard drive, there should be a hidden copy of Windows which can be RESTORED to the main partition during boot-up and pressing the proper F-Key. It will ERASE anything on the drive and restore it to the condition it came in.
Obtain the proper discs for your laptop from the laptop manufacturer. You definitely CAN get them, although you may have to pay $10.
Regardless of how you reinstall your original Windows you should then do this:
#1) Microsoft Updates (set to Auto update. Be careful of some Optional updates, especially drivers. Just use the ones from the laptop website and ignore these).
#2) Driver updates. Get these from the site for your EXACT laptop model and version of Windows (i.e. HP CZ36-ca running Windows Vista 32-bit). Not all drivers may apply if there are different options such as different video cards.
#3) BIOS. Update this if out of date. Pretty easy. Find your BIOS version and then download and run the proper EXE file if a newer one is found.
#4) Software for your laptop: Some laptops even have a program that manages drivers. I've seen some of these work, but many don't detect the new updates.
#5) BACKUP. Create backup images using either Acronis True Image (free version available of a Seagate or Western Digital drive installed. Get from the drive site). Otherwise buy a copy, use a different Imaging program or use Windows 7 Image (does Vista have this?):
Image #1: Immediately after installing Windows and ACTIVATING it. (always keep this copy as you know it's not corrupted by a virus or software glitch)
Image #2: After all updates and drivers are applied. I suggest you keep this one too. Possibly delete Image #1 if you're satisfied this is rock solid.
Image #3: Keep another backup which you replace periodically, such as every month in case you need to RESTORE it.
**IMAGES should be stored on a USB hard drive. If your main drive fails completely simply restore the latest backup image. If it is simply corrupted beyond fixing easily, recover any important data first before restoring the latest backup, then copy the data back over.
Best of luck on fixing it if you wiped the partition, but let one thing be absolutely clear: Just because your computer doesn't have restore cd's in the box, doesn't mean you can't make any. Its really one of the first things you should do when buying a new laptop. This has been well established in the industry since like 06 times. This is NOT to be confused with the built in utility in windows 7 to make a repair disc, or to clone the entire drive. A simple step I see ignored so many times.
Every company now gives that option. If they don't, well, that is when you should complain to the manufacturer.
This program will make driver hunting easier if you go that route: http://www.aida64.com/. But keep in mind thats ill advised if the reasoning is thats the only CD you had. If your reason is compatibility of programs, then thats a different story.
If win vista or win 7 was preinstalled on the Laptop - the system has a backup of the os on a special partition which is possible to restore to factory defaults - and all laptops are made this way - the reason they don´t come with cd´s are that they are cheaper this way.
If the laptop is Win Vista or Win 7 compatible you might get alot of thoubles finding drivers for Win XP or it might be impossible .