How did you restore? Did you use the Dell supplied discs for resetting to factory settings? Reinstall from a Windows disk? Restore from a backup? It sounds like you might've just installed from a Windows disc, and that's a process which could easily end up with missing drivers, causing your problem. If so, you need to get the discs for restoring to factory settings from Dell.
I restored my Dell Optiplex 760 yesterday because it was starting to slow down a bit. I've restored my old laptop many times so I was used to the process. After restoring, my computer (which I've recently updated to Windows 10) started back up and returned to the start up screen which shows the time etc. Usually id press enter which would bring me to the login screen so I could type in my password but for some reason, my computer isn't responding to any of my external devices like my keyboard, mouse and speaker even though they all light up still. Usually if my keyboard doesn't work, I go into my settings to fix it but because neither my mouse or keyboard are working, I can't even get past the start up screen. I've tried plugging them into different usb slots and turning my computer on and off but still I can't fix it. Someone please help