How can I bring back these good feelings I used to have?

I used to be happy all of the time and loved to eat. A lot of things have changed recently. I’m not getting along with my family, I’m losing confidence in myself, and every little task makes me feel depressed.

I just want to wake up and feel young, beautiful, intelligent, and look forward to seeing some cute guy and flirting with him. Or maybe just that old feeling of "this is a new day!". I’m only 21. Why is life so sad now?