McPartlin has stepped down from his TV commitments after being charged with a drink-driving offence.
Singer-songwriter Barlow told The Mail on Sunday’s Event magazine of his own career low when he was dropped by his record label, saying that it is “hell when you are in it because you can’t see a way out”.
“And when you have the whole world watching it makes it three times worse, because you can’t escape it.”
Of McPartlin, who is one half of TV presenting duo Ant and Dec with Declan Donnelly, Barlow said: “But what Ant should know is that he can come out of this.
“He needs to get well, but he can come back. I’m a big fan of those guys. He needs to know that everyone loves him and that doesn’t just go.
“When you’re in a bad way, you don’t realise it, but everyone is really rooting for you to get back on your feet.
“You just have to believe you can do it.”
McPartlin, 42, was charged by postal requisition on March 21 after allegedly being involved in a collision with two other cars while he was driving his Mini in Richmond, west London, on March 18.
The TV presenter was due to appear at Wimbledon Magistrates’ Court on April 4, but the hearing was adjourned to April 16, a spokeswoman for the court said.
After he was charged, ITV announced that Donnelly would go on to present the final two episodes of the latest series of the duo’s programme Saturday Night Takeaway on his own.
Barlow, 47, said he was in the grips of a difficult time earlier in his career, after his pop group Take That disbanded and he was dropped by his record label in 2000.
He said: “I remember waking up one morning and I was enormous.”
He said he was “a mess”, that he was “not the man” his wife Dawn had married, and that he went to see a doctor for his depression and weight issues with her support.
He added: “I hate to see anyone going through a really tough time.
“And that’s why I sympathise with Ant.”
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