As much as we might like to go back to 1968 or any other "simpler time" which wasn't riddled with today's problems we can't.
A detailed study would show you only that it was a different time, with different problems which also weren't solved satisfactorily by the government of the day.
There were a lot fewer people. There was a lot less pressure. There were no cell phones and no internet. Russia had the largest prison population in the world and the War in Vietnam was raging. The AR15-style weapon with a high-capacity magazine was not available. Blacks were second-class citizens, gays stayed in the closet.
Which one of those would you bring back to prevent mass shootings? Or perhaps you can think of others...
Point being...you can never go back. You can't make today like yesterday. But you can make tomorrow better than today.