How To Induce Periods?

my wife age is 42, we have twin children of 18 years. her last period was started on 20th December 2014 morning . as per expectation it was start 15th to 17th January but did not start yet. Now she want to start it as early as possible because we have no plan to be get a baby even she is pregnant or not. please advice me a safe medicine & reasons. Earlier on 4th Dec. she had diarrhea & was administered 64 bottles of clyne.