Writing for sci-fi and need info about preserving life?

Okay so in a calss for school called sci-fi we have to write a science fiction story that involves preserving life. I was going to write something along the lines of cryogenics.... now what I need is detailed info about whether or not someone could be frozen then thawed and not be dead? Or is there another way to preserve someone for lond periods of time? Similar to cryogenics? Now it doesn't have to be set at this time but it does have to make sense as far as the science goes, so no made up bs answers is how my teacher put it pretty much.... yeah any help is nice thanks :)