I've been diagnosed with phimosis stage2 i can retract completely when penis is flaccid,about half until head when erect.is surgery my only option?

Old-fashioned way: A guy whose foreskin pulls back all the way when not erect, but is tight during erection, should be able to fix the problem by stretching his foreskin twice a day until it slides back and forth over the glans (head of the penis) easily during an erection. The simplest way to stretch the foreskin is to create an erection and then pull the foreskin back to let the glans stretch the foreskin.

Maybe..: There is a risk if you try to force a full retraction and it gets stuck. It sounds unlikely if you can get it retracted when flaccid but it could form a tourniquet at the base and lead to an emergency by blocking blood flow to the glans. You can consult with a urologist who may be able to do a minor procedure (not a circumcision) that could fix the problem.