An unemployed New Jersey man won a $273 million Mega Millions lottery jackpot last week after a stranger found and returned the winning ticket that he had left behind on a store counter.

The man, Michael J. Weirsky, told reporters on Thursday that he lost two tickets immediately after he bought them at a QuickChek in Phillipsburg, N.J., on the day before the lottery drawing. He said it was the result of “the typical cellphone deal.”

“I was paying more attention to my cellphone,” he said at a news conference. “I put the tickets down to put my money away, then I did something with my phone and just walked away.”

Mr. Weirsky had spent hours searching for the tickets when he got to his home in Alpha, N.J., near the Pennsylvania border. He was convinced they must have gotten lost there, and it was not until the next day that he decided to ask a clerk at the store if anyone had seen them.