M28, could sneezing and coughing 50 days after surgery cause to recur hernia(note it was large inguinal hernia, repaired with mesh in open style)?

Possible: Unlikely but feel and check and see the surgeon. It does happen.

Yes, it's possible: Anything that will raise the pressure in the abdomen can exert the same pressure on a hernia and cause it to recur, despite having just had a repair. While 50 days is right within the threshold of regaining maximal tissue strength, hernia repairs can fail at anytime. Even months or years later. Have your surgeon re-evaluate.