Empty and Lonely

I cannot explain why I have been feeling lonely and empty lately. My mind is not fully committed to the presence while my physical body has low vitality and my spirit disappeared. I do not have any motivation, purpose, or any target to be determined to achieve. In addition, interacting or communicating with other people is undesirable. Inside out, I am just an empty space without any ideas, sensations, or energy. No matter how many I am surrounded by, I still feel lonely. There is no spark, no meaningful connection, no inspiration. What's wrong with me?