Is there no other way othr than circumcision to fully stretch back the foreskin of penis. My age is 23. Kindly suggest some exercise or medicine?

Prepucium . Try to retract it a little at a time several times a day when going to urinate or after showering( do not force it completely down to the crown of glance). You may use some lubricant like baby oil, KY jelly. Or astrolide.
No exercises. Physically stretching a tight foreskin over the penile glans can only lead to skin splitting, then scarring and ending up with a worse problem. Steroid cream, such as Betamethasone , when applied ywice daily for many weeks to the tight area may loosen things up. 50% will tighten up again after applications cease. Alternative is a minor dorsal slit through the tight area, this preserves foreskin.
It can be done. Where there's a will, there's a way, as the old saying goes. First, one needs to find a primary care doctor or urologist who has an interest in this issue. If one is able to tolerate brief mild pain, then some force can be used (afterward however, one must off and on stretch the skin all the way back and forth to prevent it from healing in a tight position). Steroid cream (triamcinolone) may help.