How old are you?
Were your periods very regular before they stopped?
Have you had much stress or weight change?
Do you use anything for birth control?
When was your last period? Thank you.
It's not unusual to miss a period or 2 when a woman is in her 40's. It's the start of the slowing down that eventually ends in menopause years later.
If you haven't done so already, I would see a good fertility doctor. There are tests that can be done to measure your "ovarian reserve", which means the number of eggs you have remaining in your ovaries. These tests can give you a good idea of the likelihood of success in getting pregnant.
Pregnancy can be difficult at age 44, even using ivf, but the doctor can help you along and also give you a realistic guess as to success. Best wishes.