i have wrongly wrote my dob 21 instead of 26 is this create any problem in BHU counselling?
Yes, any error in the application form that you have filled up might cause a problem at the time of counselling. But you should hold your composure and talk to the authority and explain them that you have made a mistake and was somehow unable to fix it. DOB is an important detail but I'm sure the admission panel will take you into consideration if you explain well.