When he awoke, he thought it was 1994 - and had no recollection of his daughters Olivia, 18, and Lilly, 15.
He even thought he had split up with his wife, Linda!
His short term memory was so bad, he couldn't remember things that happened only hours ago.
This year, his family are hopeful that they will have a Christmas to remember, as Gary's memory has started to improve, little by little.
Speaking to the Sun, his wife Linda, of Basildon, Essex, said: "Last year, Gary was crying on the run up to Christmas as he knew he used to love our celebrations. By Boxing Day he couldn't remember anything.
"This year his memory is much better, and we're looking forward to a memorable day together."
Imagine losing 17 years of Christmas memories - good luck with your recovery, Gary!
More on Parentdish: Mum can't remember her babies after car crash wipes her memory
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