Cryogenics has always sounded like wishful thinking to me -- a sort of high tech reincarnation based on a purely speculative pseudo-scientific idea. Whether or not it has any foundation in real science is debatable.

Freezing might preserve you, but your cells will burst as you thaw, much like freezing fruits/vegs makes them fine for cooking but no longer for fresh crispness

The less complex the life-form, the better able it is to survive, dormant, in extreme cold.
Some fish can survive in a state of almost zero metabolic rate, for a very long time, encased in ice,. However, they would not survive the ultra low temperature of liquid nitrogen. Even certain hibernating mammals can lower their metabolic rate to survive in deep, arctic winter, but they still need to metabolise enough to remain above freezing. Once temperatures drop too low, metabolism stops completely.
Think of it as a car engine tticking over very, very slowly. Only when the fuel supply is increased will it rev up. Cut off rhe fuel completely and the engine stops.
In effect, It "dies". A very simple, low tech engine could be booted back into life with a crank handle. A modern engine, with metal alloys and delicate injection systems involved, would deteriorate and be impossible to restart by cranking it - unless it had not been exposed to extreme cold.

No current hard evidence that it works. Lots of people are currently being cryopreserved, but none have been successfully revived. The thought behind it is that we have not yet discovered technology that would be able to treat the negative effects of cryopreservation and the cellular crystallization that occurs. The thought is, though, that the method is intended to preserve enough of the brain information to permit future revival, so I'm thinking self would be sustained as well. Guess we won't know till we start waking those zombies up!