So you are actually then trying to 'restore' the device, as in go back to the original state (prior to any problems)? A reboot, as I said, is just turning the machine off and then back on.
If you are in deed trying to restore the device to its original state, like when it was purchased, then you are going to need to either have the needed data on the machine already (secondary drive or another drive partition) or you will need a CD/DVD/USB with the necessary data on it.
NOTE: These will only work if you can get into the system. They will not work if you can't even get into Windows.
In Windows versions prior to 10, you should be able to...
1. Go into "Control Panel" and then click "Recovery."
2. Next click "Advanced Recovery Methods."
3. Now click "Return your computer to factory condition."
And in 10...
To do this go to "Start", then "Settings". Next choose "Update & security" and then "Recovery" Here click "Get started" and select the option you wish to use. From here just follow the on-screen instructions to restore Windows 10 back to how it was upon leaving the factory.
OR try the following, if you can't get into Windows...
1. You will need your Windows OS (Operating System) CD or bootable Windows OS USB device.
2. Connect the bootable USB device or insert the CD into your computer.
3. Now use the "F2, F12 and Delete" keys enter BIOS setup.
4. Click "Repair Your Computer" below the "Install Now" button.
5. While you are in the "Repair Your Computer" open "CMD" (Command Prompt).
6. When you are in "CMD" type “diskpart” then type “list volume”.
7. Next you will be in "list volume". All volumes should be shown.
8. Find your system volume, where the windows are installed and then type “select volume ###“(system volume C) shows on CMD. Ex. select volume 3.
9. After you have selected the volume, type “ACTIVE“. Your system partition is active now.
10. Now type ”exit” to leave diskpart and then type ”exit” again to close CMD.
11. That’s it now RESTART your computer.
This should work, if you follow the steps correctly.
NOTE: When typing in anything, do not include the quote "" marks, otherwise things will not work correctly.