4 years ago I tried to cut my finger off in public
What triggered you to try to harm yourself?
I have many reasons, the biggest one being the pain.
I understand that pain can be unbearable, but trying to fix pain by cutting off your finger and creating more pain doesn't work. See the doctor and find out what steps you can take to resolve the issue with your finger.
I was on drugs and drunk.
That sounds like that might have been part of the big problem. If you want to hurt yourself when you are under the influence, maybe you should not drink. It is not okay to do things that will purposely harm yourself.