How if somepony is sad what would あなた do?

What I do in such situation is quite ironic actually. I'm a pessimist and my perception of the world is dark, yet people seem to find me with their problems. And I try to help them, 表示中 compassion and comfort. I believe in the power of words, so I'm always open for a deep, lengthy conversation. People tell me their troubles and I try to give them suggestions and cheer them up.

Ignoring the 'somepony' (I have my reasons, for seeing it as useless).

I don't know what to say about this.
Except.
Grab Pinkie, bring up hugs

Beat the shit out of whoever made them sad.

*Pulls out 読書 glasses*
This is my training, therapist job here I come.

i would try to make that ポニー smile

I would hear out his/her problems and try to solve it as much as possible によって saying some positive things to him/her または try to settle things rationally with the offender...speaking to people about your problems instead of keeping it all bottled up makes あなた feel a bit better,i know from experience :)

make them listen to ポニー tunes :D
also, tell jokes and try to make them laugh