Yes you can.
You need to find your positive qualities, know your flaws and negative qualities and over come or accept them. Everyone has something they are good at. Maybe you are a good cook, creative, an excellent writer/artist, musician, thinker, conversationalist, etc. Make a list of things you are good at, anything and everything. Post it somewhere that you will see it everyday.
No one is perfect and everyone makes mistakes. Learn from the mistakes you've made and don't dwell on them, accept it and move on, same with any regrets you have. You can't turn back time, what's done is done, what's gone past is gone, which is really hard for some to do, many of us here have a hard time with that one.
Not everyone blows smoke out of their ass. Ask someone you know who will be honest, find out what they think your positive qualities are. Maybe someone has said something nice or what they like about you. Even if it's from your parents or friends, someone you think might be biased, they are still giving you positive reinforcement.
Change what you can that you don't like about your life. The smallest of changes can bring happiness.