So I have this simple question. Is there an adaptor than can turn my laptop's minidplay port to hdmi input? I know there are adaptors to hdmi output but I have found nothing about hdmi input (so I can turn my laptop's screen to a monitor)
Not sure what you're asking. Do you want an external monitor via DP to Hdmi or use laptop's screen as a display from an external device?
If the latter, no. But is possible to outsource video from DP to Hdmi external display. See display guide in my sig for further details.