A year and a half of sobriety down the drain.
I'm sorry to hear that. What caused you to use again?
I've been lonely and depressed.
Depression and loneliness can be very difficult to deal with. Using drugs or alcohol is not the solution though. You should speak with a mental health professional instead so you can get therapy instead of using illicit substances.
I don't want to use drugs anymore.
It's good that you want to stop using drugs! You were sober for a year and a half, so you can definitely do it! There are plenty of resources to help you kick your drug habit.