"Is it happened...?" is WRONG. The correct way: Did it happen again?

Magenta, thanks for your comment. Rosia, good point about present continuous form. I liked it. Thank you too.

Magenta, thanks for your comment. Rosia, good point about present continuous form. I liked it. Thank you too.

Magenta, thanks for your comment. Rosia, good point about present continuous form. I liked it. Thank you too.

You can also say, "Is it happening again?", in the present continuous form.