Factory reinstall

Hello,

My sons laptop is a gateway, running windows 7. It has so many pop ups that it's impossible to log into email.
So, last night we moved all files to an external drive. After 12 hours we were able to begin the process to restore back to the factory settings.
Toward the end of that process, the screen went black & a white Install Window error box popped up reading, "The computer restarted unexpectedly or encountered an unexpected error. Windows installation cannot proceed. To install Windows, click "OK" to restart the computer, and then restart the installation."
Each time I click ok, the screen comes back black & the same error box & message pops up.
I have tried to remove battery, unplug & hold power key for 15 sec, to hard restart...that was unsuccessful.
I have tried to set default settings in the utility manager, that was unsuccessfully.
I have tried to run in security mode & that was unsuccessful.
I have no idea what else to try & I'm not able to find the factory CD'so that came with the purchase of this pc.
What can I do to finish the window reinstall?
Please advise.