my laptop is Toshiba satillite C855-S5303 working with windows 8 when I buy it. when happen an error and stope windows 8 from work. the serviceman change to windows 7,after one moth microsoft say it is not geniuin ,error code OxC004F063. then I want restore factory setting windows 8,thanks.
When you turn the machine on, if you don't see a Recovery option on the first black screen that shows up for a short time, there is no way back. Your only option in that case is to validate your Windows 7 system by buying the key from Microsoft then take the option to upgrade to Windows 10.
There's only twenty seven days to go before that offer expires and you would have to buy W10 or stick with 7.
Alternatively, you could go back to the repairman and demand a proper and legitimate fix this time.