There are quite a number of science fiction stories, describing time loops. A common theme is that of the man who is sent back in time, after being told that he must not change anything. He accidentally kills a butterfly. He then returns to his original time, only to find that in killing the butterfly, he has changed history so much, that he has no world to come back to. All science fiction with a philosophical element is worth reading.
Science fiction is very good for shaking up the grey matter in the brain.
However, it does appear that while the future is very highly variable, the past is fixed for ever. No one can change the past, but any stuck emotional charges can be drained or abreacted out of the mind. Abreaction is a psychiatrist's term for the therapeutic discharge of old, and obsolete emotion. This is commonly in the form of laughter or tears, but not necessarily so. From time to time, past life incidents may surface.