Hello, I am 28 years old and my problem is that the head of my penis is not coming out. I tried to strech it a lot but it just pains but does not come?

Phimosis. It sounds like you may be suffering from phimosis, which is a condition found in uncircumcised men and boys in which the glans, or head, of the penis becomes trapped behind the foreskin. There is usually a tight ring in the foreskin that makes it difficult to retract the foreskin over the glans. This can be problematic, and I suggest you see an urologist for an examination and treatment.