How to make my gf happy everday???

This many days I found that she not happy, she look sad i think she have alot of stress with her friends and with her little bro.. but she not show it to me.. she just say nth to me and make me happy but i knew she not so happy.. how can i help her out this problem?? I really want to help her, when she sad i also feel sad too... I want to see my happy gf like b4 what can i do?? any one can tell me? pls give me some advice... thx in advance. . ( if u see pls don ask me, bong don want oun see te, just want to help oun )