What Causes Absence Of Periods After Taking Mepret For PCOD?

Basically my wife was suffering from PCOD and was on medication for it and after around 1 year we got her diagnosed and after usg we came to know she has recovered and Dr. Suggested her to have mepret in place of Yasmin. But by mistake she took it on 25th day instead of 20th day and now its 6 th day after completion of the dose but she s not having her periods. What should be done next. We are worried.