My wife usual menstrual date is 25th day of the month.she mestruate on 14th this month after taking medicine.when will she ovulate next?

Impossible to answer: That is unknowable. If an irregular cycle occurs then one cannot predict easily ovulation and pregnancy must be more carefully protected during such irregular times.

Ovulation: Ovulation occurs consistently about 14 days before your next cycle. If you know how many days there are from the first day of the bleeding to the next during your normal cycle just subtract 14 days. This allows you to predict when you should be ovulating. If cycles are irregular then prediction is almost impossible.