When someone tells you, "You've changed," it might simply be because you've stopped living your life their way.
You can learn great things from your mistakes when you aren't busy denying them. Read The 7 Habits of Highly Effective People.
Learn to love yourself first, instead of loving the idea of other people loving you.
Sometimes you need to distance yourself to see things clearly.
In life, if you don't risk anything, you risk everything.
Learn to appreciate the things you have before time forces you appreciate the things you once had.