No backup, how do you want to restore the data?
There are applications that allow you to see data partially after deleting them if you have not spent much time, with a bit of luck, while viewing all the information that contains your memory and selecting one by one each file that is very incomplete.
After more than 3 hours, I managed to recover half (only half of the image was visible) that I accidentally deleted.
I can not recommend an application, it has been used for years and I do not remember the name. Doing a search in google you will find different tools.
But keep in mind, without backup you can not recover all your data on any device. Xiaomi has several ways to make backup copies and for the photos I use the google application (highly recommended).
I feel your loss. I never experienced anything similar with my MI5 and it still works perfectly.