This is a known issue and is being looked at by development.

A small amount of games was affected by this due to a hickup in the database, but at least all players in those games were affected equally. This is of course far from ideal but could have been worse. At this point there is no real way of restoring the old research state, sory :/. If you spent gold for the researches in that game, please write a support ticket to receive compensation.

You staff must realize that days upon days are being wasted having to research the same crap that we have already researched, not to mention all of the valuable rare materials that have been wasted. It's put a huge standstill in production and ruins some strategies that are based on research unlock time. I have been HUGELY affected by this in my game (Code:1892749) as have many others. I request that instead of just having to "deal with it" we receive some sort of compensation. I've put together that math and since the game is on day 13, there is the potential to have researched (at most) 44,200 gold worth of troop unlock time (not mentioning using gold to buy resources to research) I believe every player in this game should receive that amount of gold (44,200) to compensate for the massive hit this has taken. I'd like to debate this in this thread publicly if staff declines my request. It isn't fair that we have spent so much time just to be screwed over by a "hiccup". Again, why should we [the players] be negatively affected by your mistake? We need compensation.

We are releasing a script now that checks which units a player has on the map. it then enables all researches of these units up to that level. In most of the cases the users will get their researches back by that. If there is still any issue left after that update, please write a support ticket.

Sorry for the inconvenience!