To restore Win 7 PC to factory condition need disc to remove all data

I have a Windows 7 computer which I need to restore to factory condition. Fortunately, all my user data is backed up, and I still have the application installation discs. The computer manufacturer sent me a disc set to restore to factory condition, but the instructions say I have to first delete all data from the hard disk else the disc set won't work. Once all data has been deleted from the hard drive, I am confident the manufacturer's disc set will restore it to the condition in which in left the factory. However, there is no way to get into the system, so I need an external disc that can remove all files from an inaccessible hard drive. It could be standalone or part of a utility suite. Anyone know where I can get one?

At first it says, "delete any data on the hard disk." But later it says, "Please remove all files from your hard disk before starting. This function will not work if there are any files on the hard disk." So I need a disc that will remove all files from the hard drive.

Is the computer the Acer 7750G-6494 ?

If yes, the computer can have a Factory restore partition that allows you to, from BIOS, launch the restore function.

If you can boot the computer, Please post a whole window Disk Manager image of ALL your drives. Don't forget to expand the columns so we can read them. How to Post a Screenshot of Disk Management
If you have a MiniTool or AOMEI Partition use it instead or Windows disk manager.

It is an Acer 7750G-6494 but trust me, there is no way to boot into it. The CD/DVD drive is 1st in the boot order. What I need is a disc which will run when I turn the power on, has an option that will remove a hidden partition (the XP SP3 virtual machine), and another option that will remove all files on the C drive. When that is done, I will then be able to run the disc set that Acer sent me (when I bought it) that will restore it to the way it was when it left the factory. Does anyone know where I can get a disc that will do that?