Irregular periods occur from numerous reasons like excessive daily intake of alcohol, smoking,intake of certain medications, weight gain,taking foods with less nutrition, stress. If this is the reason then just stopping this improves the condition and doing meditation, yoga and morning brisk walking is helpful. Other reasons like abnormality in genital tract, hormonal imbalance or PCOD can also be a cause. For this things, you need consultation, so I suggest you to consult a gynecologist to rule out this things.