Is a divorce valid if it was issued by the husband under duress and coercion, and is it permissible for him to return to his wife after this irrevocable divorce by three pronouncements?

If you uttered the word of divorce once, it is a revocable divorce (ṭalāq rajʿī), and you may take your wife back before the expiry of her waiting period (iddah). It is recommended to have witnesses for the reconciliation (rajʿah), and the wife's presence is not required. As for the court's decision regarding an irrevocable divorce (baynūnah kubrā), you must approach the court and inform them of the truth to cancel the previous decree. From a judicial perspective, it is difficult to live with a woman against whom an irrevocable divorce decree has been issued, but from a religious perspective, only one divorce has occurred, and you may take your wife back. In fact, some scholars are of the opinion that a triple divorce counts as one. Your situation might also be one of duress (ikrām), and the divorce of one under duress does not count, but this requires a judge's ruling after knowing the details of the incident.