On some laptops, as it is booting up before the admin password prompt ...you will see prompts. F2 is usually BIOS, F10 (or some other "F#" function) might be start recovery...if that is the case press F10 and it will go through the recovery process and reinstall the OS. The recovery is usually on a separate partition and accessed through a "F#" prompt.
If the above does not work...
You should not have to go out and buy a Windows Operating System. You just need a Windows install disc, and use the license key (usually located at the bottom of the notebook) to do a new reinstall. However you might need to download the drivers as well if you do not have the original manufacturer recovery disc.
Or just install Ubuntu for free and not have to worry about tracking down drivers and worrying about viruses later on....
If the above does not work...
You should not have to go out and buy a Windows Operating System. You just need a Windows install disc, and use the license key (usually located at the bottom of the notebook) to do a new reinstall. However you might need to download the drivers as well if you do not have the original manufacturer recovery disc.
Or just install Ubuntu for free and not have to worry about tracking down drivers and worrying about viruses later on....