The 22nd amendment to the US Constitution bars Trump as a viable candidate for the Office of the President. It would require an additional amendment to be possible and there's no way that 3/4ths of all US states will agree to that shit.
The only potential loophole that I can discern is that there's no clear consensus on if Trump would be allowed to run as Vice-President on someone else's ticket. If he can, then, theoretically, he could run for VP and then have the elected President immediately resign, making him the President again.