When the periodic cycle is not of 28 days, it is termed as irregular periods. There are many reasons for irregular periods. The major cause is due to changes in hormones. 
Pregnancy can also be the reason. The other reasons are stress, Change of place, diet change, Excess of exercise, illegal usage of drugs and breast feeding. 
With a control of all these issues, the irregular periods can be treated naturally.

Irregular periods is due to your cycle length, So don't worry about that it will automatically change. If the cycle length is found to be same, then maintain a regular diet with plenty of fruits vegetables and water.