To get your ex-girlfriend back, you have to be rational and make a logical plan.
Taking drugs and alcohol won't help you to get her back and may ruin your chances with her.
Doing nothing won't help either.
Get your thoughts together and begin to make a plan and execute the best ways to get your ex-girlfriend back.
A calm and calculated approach is the best way to make up quickly.
Keep your head where it should be.
Be patient.
Don't try to chase after her.
She will feel nervous and unprotected.
Don't make her think that you are stalking her.
Give her enough space to think things over.
Give her time to calm her feelings and emotions.
Respect her pain and loneliness.
Your presence will only intensify them.
Don't communicate with her.
Give her emotions and feelings a break.
She is suffering an emotional stress at the moment don't add to it.
Let her miss your shoulder that she used to cry on.
Let her miss your comforting presence and the security of your loving arms.
Let her cope with her grief alone.
When she has overcome her grief, it is time to start implementing your plan to get your ex-girlfriend back.
Don't plead or beg for her to take you back.
Pleading and begging will make you look miserable and pathetic.
By doing this you will only lose your dignity and her respect.
You will be under her power from then on.
 A woman does not take back a man that she does not respect.
She does not need another doormat.
Do not make threats.
It will only make her defensive or nervous.
Worse it may arouse her antagonism, and that would put you somewhere beyond zero visibility with her.
Threatening your ex-girlfriend will give her an excuse to find a better man as soon as possible.
Keeping your wits about you will enable you to act rationally and plan your steps carefully and logically.
Keep your patience and make that plan for the best ways to get your ex-girlfriend back.