I am 24 years old and I don't get periods regularly. A doctor suggested me to take penorit. Now without the usage of penorit tablets I dont get period?

Penorit not a cure. Penorit, which is a combination of two reproductive hormones (norethisterone & ethynyloestradiol) is used as a "morning after pill" or emergency contraceptive. It may, in the right circumstances, induce a menstrual period, but it won't address the underlying reason that your periods are irregular. If you need to regulate your cycle, there are better options. Please talk w/ your doctor.
Need more info . May be you have Polycystic ovarian syndrome. You should have a thorough evaluation of ovarian and thyroid harmones.