Greetings,
First,
Alcohol/tobacco smoking/Drug or any kind of intoxication is not the solution to any of your problems.
Stop it.. it will only let you down.
Coming to the next stage:-
Peace of mind can be achieved only when you are happy (or at least used to) your circumstances and the surroundings.
You cannot control the circumstances in which you are in the present, but you can always improve them for yourself and those around you by working towards a better future.
There are many ways in which you can achieve happiness but it all depends on the things that you do that make you happy. You might like sports, music (instrumental), eating, travelling, sleeping, playing video games, cycling, hiking etc etc. do not hurt the life form).
In my suggestion I want you to start by identifying the things you love to do and be very honest with yourself. It doesn't matter how you look like doing them because your aim is not to look good doing it, but to be satisfied and happy.
The key to my success was Never Giving Up.
No matter how difficult or harsh the circumstances, perseverance and determination allow you to achieve what you want.
Try these:-
Be sure of your choice.
Stop worrying too much and enjoy the journey of life.
Help others, including humans and animals (seeing someone else happy can bring happiness to your life too).
Stop being negative and critical about everything (it's okay to slack off sometimes and try different things).
Try to mingle with your surroundings (try to engage in conversations with different people and try to understand their thinking and way of life).
Stop judging people.
Definitely indulge in some sporting activities (something that drains you of energy / gym is also an option).
Try reading.
Try meditating.
Spend some time with the elderly and children.
There is a lot you can do to be happy and attain peace of mind. Whatever you do, try to do it regularly so that you can reduce your stress and tension by doing these things.
“A person who never gives up is irresistible”, focus on your goal of achieving peace of mind and one day you will surely achieve it.
May god bless you.