Hi there, and welcome to the forum.
It sounds as though the laptop has McAfee Endpoint Encryption installed. This is a full disk encryption (encrypts the entire drive rather than specific files/folders), and in order to access the drive/boot into the OS, you have to pass the preboot authentication.
The good news is, is that (assuming there are no hardware faults) there is no need to replace the hard disk or any other components.
You need to repartition and reformat the hard drive and install a new OS onto it. If you have a valid Windows license you could install Windows, or alternatively you could download and install
Ubuntu or
Fedora Linux. Both of these Linux distributions are available free of charge and are very easy to install. They're also simple to use and are bundled with useful software such as office suites etc.
See
this Youtube link for a basic tutorial on how to use Ubuntu.
There's a whole host of tutorials and guides (for both distributions) available on Youtube.
