How can you tell if you are depressed?

Hi zhawee! I'm not sure if it was considered depression but I felt really down at one point in my life. I just 'slept' for a couple of days. I did not go to work. I did not take a bath. I just listened to music. I almost did not eat anything. I did not want to speak to anybody. When somebody asks me what is wrong with me, I did not know what to answer and I certainly did not want to talk to anybody at all. Even my boss came to our house to check what is happening to me but I did not want to face anybody. All I wanted then was to just doze off to sleep and live in my dreams. I felt terrible every time I wake up. I felt so sluggish and indifferent about the world. To sum it all, I shut myself down from the rest of the world. I cannot remember how I snap out of it but the following days, I moved around like a zombie.