From where? It isn't on the drive and you have no Windows 7 DVD. You would have to buy something in order to "reload" Windows 7. Check prices https://www.amazon.com/Microsoft-Windows-Professional-Old-Version/dp/B002DHLVII You might do better saving money and getting a modern computer with Windows 10. I don't advise Windows 11 until it is at least 6 months old and drivers for things like printers are out. Otherwise, you other hardware won't work. If all you have on the hard drive in the Dell computer is linux, then imaging/cloning/restoring is not going to work. You can not magically get Windows 7 back on a computer if it is not currently installed. You could get it back if it were installed as part of a dual boot.