Can you lose your soul...?

The short answer is "No."

A law of physics states (this is my paraphrase) "Nothing is created and nothing is destroyed." This applies to your soul.

At our core, our soul level, each and every one of us is good. 

We can become bewildered and do things that aren't consistent with our deepest self, our core. But we can't lose that core, our soul.

Sometimes we lose our way and do things that aren't consistent with our deepest self, our core, but whatever we ever have been, we are still, and we can find our way back.