What Am I Riddles

Question: When you close it, you see mysterious and funny looking images. But if you open it, the mysterious images are gone. What Am I?

Question: I can be seen, I can be not. Thanks to me, you'll fall in love. I mostly am sweet, but once I were sour. You can receive me, you can't just buy me. You only can send me, or simply share me. What Could I be?

Question: What is that comes out of a man, has no hand and has no legs but can make a hole on the ground?

Question: I am lonely and yet you use me a lot. What am I?

Question: You will always find me in the past. I can be created in the present, But the future can never taint me. What am I?