My wife have irregular cycle of periods but its now 50 days she is not getting them and she is not pregnant. what should be the problem.

Missed period: You didn't mention your wife's age, but if she is young enough, and this has not happened before, i would recommend that you wait for 90 days to see if it comes. Many factors can cause missed periods: age, stress, medical illness, medication, recreational drugs, hormonal imbalance, obesity and many more. You would need to see your gynecologist for a consultation.