Marked as Unwatched files watched on a specific date

Hello!
Some time ago I had some guests over that seem to have messed with my Kodi. More exactly someone seem to have marked everything as watched (at least the series). Now, while looking in my Trakt history I pin pointed when this has happened to specific date and time.
Can I marked as Unwatched all and only the files that were marked as Watched on a specific date and time? Or can I marked as Unwatched everything taht is not yet watched on Trakt?
Thanks!