Try having her take a shower and then praise her for it. If you have a pool, let her go swimming and then praise her for it. Some people buy their kids movies and books, etc. If you bought a radio, throw her on it and praise her for dancing. Same with playing with toys, playing in the sandbox, watering the flowers on the right side of the livingroom wall, etc. Give her lots of attention and treats and her mood should pick up.
Try not to scold her. If she's being naughty, redirect her (move her to a different area to play). Hope this helps.