What is the ruling on saying "if only" regarding a missed event, with the belief that changing the cause would have changed the outcome, and is it permissible for a man whose house burned down to say: "If only I had returned earlier, I would have been able to save the situation"?

The use of the word "if" (لو) is prohibited if it expresses longing for a missed worldly matter, such as the owner of a burned house saying, "If I had returned home, it wouldn't have burned," or the failing student saying, "If I had studied, I wouldn't have failed." This is because means are effective unless they are contradicted by divine decree. The hypocrites said after Uhud: "IF WE HAD ANY SAY IN THE MATTER, NONE OF US WOULD HAVE BEEN KILLED HERE." Allah responded to them: "SAY: 'EVEN IF YOU HAD REMAINED IN YOUR HOMES, THOSE FOR WHOM DEATH WAS DECREED WOULD HAVE GONE FORTH TO THEIR PLACES OF DEATH.'" Thus, means are of no avail if they are contradicted by divine decree.