There are presently two main camps in the Philosophy of Time, which are given the arbitrary labels "A", and "B".
A-theory says that the past and future do not exist; the future is just a soup of unwritten potential that cannot be explored except through the progression of the present. The present "writes" information into history in the form of scars, marks, movements, momentum and other artifacts in spacetime which we can explore, but the past itself is not a physical domain which can be traveled to.
B-theory says that all points in time, past, present and future exist in their own way, and that we can only perceive the present, which is an infinitely brief transition of when the future becomes the past. This view facilitates determinism easily, but is fraught with problems connected to other aspects of philosophy of mind and cosmology. For example, causation becomes a nightmare to explore, rather than being a straightforward chain.
Neither of these have any connection to Multiverse theory because M-theory is a matter of theoretical mathematics with connection to cosmology, not philosophy of time.
And so far there has yet to be an indication that time could ever go backwards. To attempt that logic betrays a misunderstanding about physics on the same level as misunderstanding the Laws of Thermodynamics.