In theory, a hash function could be reversed in a way such that you can take the hash and calculate every potential input with a range the input having a data size of 0 through the maximum.
That is not reversing a hash, that is called finding a collision.
Theoretically and practically hash functions (both cryptographically secure and insecure algorithms) are and will always be irreversible.
To put simply if you can reverse the following function and tell me what `a` and `b` were you can also reverse hash functions:
a + b = 2314