I did a factory reset on my phone and when it rebooted the phone was reset everything wiped out and reset. However after turning off and chargin phone overnight, I turned on the phone and it was back to where it was before the reset. How did it do that?

I noticed one other time when I went to delete a text message thread that the thread disappeared but the next day after turning off charging and turning back on the text message was back. What gives? How is it recovering everything that is deleted? How do I get it to stop doing this? Would it be possible to do the hard reset and then turn off what ever is doing this before turning back on? So the hard reset holds?