It was in 1982 when Mr Clarke paid him a visit as he lay in a bed at Leeds General Infirmary following a car crash.
Today the pair were reunited on the 30th anniversary of the accident, to raise awareness of brain injury support services.
Mr Sharp’s brother, Michael, 53, who organised the visit, said: “It’s a mark of the man that he came to Richard’s bedside unannounced in 1982.
“For him to come back without hesitation now is amazing and we’re thrilled because he’s our hero.”
Mr Sharp, who was 19 at the time, was seriously injured when the car he was driving hit a lamppost after swerving to avoid a lorry on Dewsbury Road, Leeds, on April 29, 1982.
While he lay in a coma his family were advised by doctors to try various methods to coax a response from him – and were told his sense of hearing may be key.
They persuaded Leeds players including John Lukic, Eddie Gray and Paul Hart, as well as Mr Clarke, to record a message of support.
The tape, which was played on a loop to Mr Sharp, concluded with the manager ordering Richard to get back to the ground because the team – facing a Division One relegation battle at the time – needed him.
Mr Clarke then gave the family a further boost by making a surprise visit to LGI.
Mr Sharp slowly came out of his coma, but remained in hospital for a year and still needs support with everyday tasks and relies on a wheelchair.
He has remained a regular at Elland Road, and Michael said: “His love of Leeds United remains as strong as ever.”
Today’s visit came at the end of Brain Injury Week.
Mr Clarke said: “I like to think that the little that myself and Leeds United did helped Richard get back to how he is today.
“He’s still an ardent fan and I often see him at the games. If we played any small part it makes it worthwhile.”