If one hyper extended his lower back while doing stretches but he doesn't have severe pain just some pain when doing some movements.is it safe to continue doing toe touches,bridges,crunches.and how to recover from it. Does it it take too long . And after how many time can he resume his old stretching routine

Individual results can vary greatly, and your particular question can only be answered after an examination by a professional. I can only suggest that you cut back, or quit your routine, or modify it greatly with guidance from an expert. Either a health professional, or trainer.

That's just the nature of any injury in that it has to be correctly diagnosed before it can be treated effectively and safely.