Yeah, @blackhawk is right. You need to backup beforehand. Doing a factory reset was the end of it, mostly.
Sadly you don't have low-level access to the eMMC memory chip, even with root is hard to get it down right, so there is no recovery of lost data available to you.
If that data was extremely precious to you your only option would be a data recovery center (which would try to read the data pages right off the chip itself externaly) but that means you should not use the device in order to ovoid overwrites of the pages and trim triggers.