McCarthy believes Doyle should take heart from Wayne Rooney and Robin van Persie in recovering from dips in fortune with Manchester United and Arsenal respectively and coming back stronger than ever.
Doyle has lost his place to Steven Fletcher and has been linked with a move to Everton.
But McCarthy, whose side face Liverpool at Molineux on Tuesday night, said: "Whether there are legs or not in Everton's interest, Kevin is not going anywhere.
"I'd be crackers to sell Doyle with two days left of the transfer window. Guess what, I'm not crackers!
"You can't be the best player all the time. Wayne Rooney had a dip in form, had knocks and niggles, Robin van Persie went out and came back and now he is flying again.
"It just happens and you have to get over it by continuing to do what you do when you were flying and it comes back - and will do for Kevin."
McCarthy admits he has been bemused by the number of rumours linking him with players during the past month, while midfielder Stephen Hunt is reported to a Celtic target.
He said: "There are rumours going everywhere. I'm supposed to have bid £2million for Nathaniel Clyne from Crystal Palace. Where on earth has that come from?
"We tried to take him 18 months ago when he was coming out of contract and that didn't happen but there is no truth in that either regarding now.
"Hunt and Doyle are supposedly going and I'm supposed to be signing Clyne (a full-back). That will be a ready-made replacement for those two!
"I honestly doubt that there will anything be happening here at all, comings and goings. We've tried and it has not happened."
McCarthy revealed he rejected Liverpool boss Kenny Dalglish's enquiry about moving the game back 24 hours because of the transfer window.
He said: "I know Liverpool wanted to play the game on the Wednesday and asked me about it and I said 'no chance'.
"We are going down to QPR on Saturday so why would I play a day later? I want as much time to prepare for both games but I could understand Liverpool's request.
"Kenny just asked me because they might be doing something (in the transfer market) and I understood it - but he understand my reasons for not changing."
McCarthy and his players went paintballing during their 10-day break from action but not far from his mind has been trying to find a solution to end a run of 10 games without a win.
He said: "The paintballing day wasn't about digging deep to find good team spirit because that is there. That was a day off from training because we hadn't got a game at the weekend, a break from the norm.
"But we are digging deep trying to do something about the results. If we weren't, there would be something wrong.
"I shouldn't be here if I wasn't trying to find a spark, something we could get results from. We are doing that all the time.
"What I can do is take positives from how we've played at Arsenal, Spurs, Bolton in the second half, Chelsea, and Aston Villa."
