You're still young and have lots of things to experience. I had very over-protective parents, so me and my sister were had our fair share of loneliness. Not being able to go out with friends and experience teen life. If I knew back then what I knew now I should have been more rebellious to want to try new things.
Find an hobby you'd enjoy and get involved. Go to the gym at school (if it as one), airsoft, cars, computers, etc. Find something that is productive which can open up an pathway for you to be around others.
Ignore those who are the party types. Growing up I noticed most people who I thought were my friends recognize my weakness of loneliness and took advantage of it. They would invite me with their crew to the bars/clubs but only to make them stand out and them getting the girls. I always ended up being the 3rd wheel.
Because you are still young you have a lot of options on the table. People you knew from school will slowly disappear as the responsibilities of adulthood begin to kick in. Focus on hobbies, and an career you want, go to college and meet other young aspiring adults.