Thank you for your question. There are surgical techniques to increase the length of the penis, but they are associated with complications. There is a cause for a visually smaller penis, but this is challenging to determine without photographs. A hidden penis (buried penis) can occur after a circumcision. The issue is not that the penis is physically smaller, but rather it is less visible due to anatomic issues. The anatomic issues can include excessive skin removed with the circumcision resulting in "hiding" of the penis under scrotal skin. Another possibility is that the circumcision resulted in worsening of the hidden penis due to the lack of repair of the congenital (born with the condition) hidden penis at the time of the surgery.
I would recommend evaluation by an experienced male cosmetic genital surgeon. The outpatient surgical technique that I use to address this issue is one that I developed and have presented my technique and results at national and international meetings.
Best of luck.
Jeffrey S. Palmer, MD, FACS, FAAP (Cosmetic Urologist -- Cleveland, Ohio)