The United midfielder filmed himself shouting and swearing in his Miami hotel room in July, while also sharing a clip of one of his friends making a lewd gesture and mimicking what may have gone on in the room.
The video briefly appeared on Lingard's Snapchat account but was later removed.
Lingard insisted to the Daily Mail: "It genuinely was a mistake to post it.
"I have a lot of young followers and I would never put that out there deliberately. It was an accident. I was meaning to send it privately to one of my friends. I was on a plane waiting to take off. Someone from the club texted me and said: 'Take the video down'.
"When I realised what I had done, my heart just sank into my stomach. I was like, 'I am done at United now. This is the final straw'.
"I was told the manager was going mad but I was in the air for two hours and literally couldn't do anything.
"When I got back I came in early to speak to the manager and apologise. He said I was on my last chance. He said I had to get my head down and that is what I have done. I am not stupid.
"There is no way I was going to let what I have at this club be taken away. On the whole I have cut down on my social media stuff now. You do what you have to do."