Garret433 :
I do not know because I bought it off someone
Well then....
1. You should have discovered the license key long before you did this factory reset.
2. You should have done a full wipe and reinstall of the OS as soon as you got this used system home.
3. The previous owner was 'required', per MS licensing, to give you the license key.
You have no idea if that original license was actually valid.
Your only recourse now is to call Microsoft and throw yourself on their mercy.
Or buy your own shiny new license key.