depends on whats making you sad. I mean if its like you are sad all the time and it wont go away just try to stay positive and if you can't then try to act happy and do random things that help. like if your upset bc your stuck in the house all day try to go to the store or walk outside or if your sad bc of someone try to fix why ever your sad bc of them and if you cant you could try to talk to someone. OR go friend shopping and make fun friends that bug you til your unsad okay this advice is probably horrid
Find something that works for you. Ride a bike, go to the pool, get a job (if you don't already have one), visit your mom, get a dog, etc. You don't need a person to make you happy because then you're just bound to have disappointment.
I always listen to music. But don't listen to that sappy stuff meant for sad people. Instead listen to something completely meaningless that pumps you up. Works for me. Because if you listen to that sad music it just makes it worse. If you listen to stuff that has absolutely no meaning and is fast paced and fun it tends to put you in a better mood.