Manford shared a screenshot of the text, alongside a tweet where he added his thoughts on the loss of the fellow comedian, as well as urging people to check in with their friends.
"I texted him a couple of weeks ago and I'm now so glad I did. If you've got a friend who you've not spoken to for a while, drop them a message and check in. It could be the last time, RIP Sean."
The award-winning stand-up comedian was known for his appearances on shows 8 Out of 10 Cats, QI and Have I Got News For You on Radio 4, the Telegraph UK reports.
Bill Bailey wrote on Twitter: "It's heartbreaking to lose my dearest friend Sean Lock, he was a true original, a wonderful comic. All my thoughts are with his family."
Actor and comedian Jack Whitehall wrote: "So sad about Sean Lock. He was such a special comedian. One of the quickest, most naturally witty people I've ever worked with. Worlds a less funny place without him. RIP. "
The Twitter account for 8 Out of 10 cats said the late comedian was a "comedy genius".
"Sean Lock was a brilliant writer, a phenomenal stand-up, a comedy genius.
"We will miss him greatly. There was no one like him."
And comedian David Mitchell said he was "shocked and sad" to hear the news of Lock's death.
"It was always a privilege and inspiration to work with him. The world should have had many years of his hilarious creativity. RIP."
Jimmy Carr said the news was "brutal" in a tweet, and shared the song Keep Me In Your Heart by Warren Zevon.
"I loved him so much. I'm watching clips of him right now - laughing & crying. I'll miss him so much."
Lock said in 2010 that he was diagnosed with skin cancer aged 27 after years of working on a building site, prior to his career in comedy in 1990. According to reports, Lock died of a different form of cancer.
Lock is survived by his wife Anoushka Nara Giltsoff and his three children.
