Is my cat depressed? ? Help?

Last month my parents have travelled to china. And i think my cat is really missing them that she got depressed. Since they left she started eating less and playing less. And all what she's been doing is sleeping. She would sleep under my bed or in her smAll cage. She now hate being petted. And she doesnt sit like she used to. She now open her arms and put ger head on the floor. Please tell me what i should do to make her feel better cuz i really feel sorry for her :(