Why would the testicle be hard and swollen a month after inguinal hernia surgery? Swelling has remained the same about 2 weeks. Little change!

Swelling. Swelling around the spermatic cord may cause a Hydrocele or other inflammatory fluid to build up in the scrotum. See your doctor and get a scrotal ultrasound.
See answer. Sometimes after hernia surgery, especially those requiring a lot of surgical dissection, there is an increased inflammatory response that may extend down to the testicle which usually improves within 4-6 weeks. Occasionally, there may be some compromise of the blood supply to the testicle (venous or arterial) which may lead to eventual shrinkage of the testicle. Suggest you discuss with surgeon. .