the most important i feel is just be there for her and listen to her...
she will feel relieve...
if she is your GF than a little hug will do with some light tapping on the back...
if she is your fren a little hug also will do but better not la, try give some gap...

basically just listen... dun be a problem solver, doesnt always turn out well...

some girls they tend to keep everything to themself, for this one i not sure how to make them talk or share...
coz currently have a friend now that consider in this type, maybe she did talk with others la... but it seems that she is not...

anyway, I am a happy person... be happy... cheers

hmm...
some of them prefer to be let alone...
some prefer someone to hug...
some just a light tap at the back can lighten their sadness...

should see how the relation between you and the girl first...
1 wrong move will end up badly...