One of my favorite movies, how did you know?
There's no universal method, but here's mine if it helps.
Step 1: Cry. A lot. Until your body goes numb.
Step 2: After (what is likely) several minutes, your brain will eventually respond to overwhelming pain by flushing out the chemicals that make you feel sorrow. (It's a defense mechanism to prevent overdose.) At this point you should feel pretty numb.
Step 3: Find something that makes you happy, be it a movie or a game or a book. Especially if it induces fond childhood nostalgia or other such memories.
Step 4: Indulge. Right about now you'll want to eat stuff with high sugar content, it'll help you recover from the sob-fest you had earlier and will naturally cause the brain to produce serotonin (the "happy chemical" as it's informally called), which will further help.
Step 5: Go find people to talk to, which you trust, and talk about
anything. Human beings are social animals regardless of whether the individual is introverted or extroverted. This is another step on the road to recovery.
Step 6: From there, continue living life, take it one step at a time until the loss is simply something you've come to accept.
EDIT
SCIENCE!