My tubes are tied .And my periods are regular after tying the tubes. I have last period on March 27th. But on April i have no periods till today . I'm confused. I check pregnancy using pregnancy kit. The result is negative. Why can't i get period on April???????? Please answer my question................

You mean your periods have been regular. There's no way for any woman to assume that will always be true. And as you age, chances are your periods will get lighter and skip months.
There's less likelihood of you being pregnant than just late or skipping a month.
All you can do is wait and test every few days if you wish.