What is the missing number i...

A man got really drunk one night in his local pub. The barman refused to serve him any more alcohol and told him he should be heading home. The man thought this was a good idea so he stood up to leave but fell over straight away. He tried to stand up again but only fell over again. He thought if only he could get outside and get some fresh air he'd be grand. So he crawled outside then tried to stand up and fell over again. In the end after falling over lots more he decided to crawl home. When he got back to his house he pulled himself up using the door handle but as soon as he let go he fell over again. He had to crawl up the stairs and managed to fall over onto the bed and fell asleep. When he finally woke up the next morning his wife asked him what he was doing at the pub last night. He denied it but she said, "I know you were there..." he maintained his innocence until "...the barman rang to say you forgot your wheelchair again...."