There is a hypothesis that says the "big bang" will eventually stop expanding and the gravity will eventually start to drag everything back to some point, which will result in the "big crunch." Then the expansion will start all over again. That idea is seen as much less likely these days as additional research shows that the expansion is becoming faster, not slowing down. However, if the big bang/big crunch idea was true, the beginning of the contraction would probably not occur until 1000s of billions of years in the future. Again, IF a contraction did occur, it <<would not>> cause time to run in reverse. Time always moves forward. The fact that galaxies might be getting closer together has nothing at all to do with making time reverse. Time needs to pass - in a forward direction - for anything to occur.