Hi Magdalena - I believe there is a slight difference between them:
'It blew my mind' = I was really, really impressed by it.
'It turned my head around' = I was really, really impressed by it and it changed my way of thinking, my opinions etc.
e.g. Prison for me was a very profound retreat, a very deep experience. I don't want anyone to have to experience what I did, but having gone through it and having come out OK, I can see its other side. **It turned my head around**, it radically changed my vision of things.
http://www.ru.org/spirituality/spirituality-and-social-justi...