Theme reseting itself?

Okay, people, noob here.
I have SKT Bakery theme-not the pro version(!), and I’ve been customizing it with Child Theme Configurator, and also, I’ve changed the .php files when I couldn’t do something in the plugin (like remove the bottom menu in footer and so)
And my problem is, for the SECOND time, my child theme reseted itself. I’ve been going mad for the whole day trying to figure out what has caused it.
I was editing something in .php and wanted to see how the original code looked, switched to it, and I couldn’t find the child theme anymore. And then, when I freaked out, few minutes later, child theme appeared, but without all the changes I made, .php files were missing and it was back to configuraiton like i reseted everything.
I tried looking trough forums and even asked my friend, gave him an access to my account, he said the theme was written oddly and that he does not know why it happened.
I am on the edge, I’ve put so much effort and patience into this, and now I am afraid to do it for the third time, because I don’t know how to prevent it from happening again :/
And sorry if I posted it into wrong topic or something, I am new to all of this.

Thank you in advance 🙂