Van Gaal had taken United to the top of the Premier League following a run of three straight wins, but the Dutchman suffered a blow on the eve of the international break when his team were easily beaten by Arsenal.
The result was a chastening one for Van Gaal. And after a fortnight spent analysing the wreckage, his mood has not got any better.
“It has been an awful two weeks,” the United manager said ahead of today’s game at Everton. ”Before the last international break in September we lost against Swansea. These are awful weeks.
”You are constantly thinking about how it happened. You cannot manage it with your players. That is what you have to do as a manager.
”But all the players are flying out, especially the last game because we played on a Sunday. They fly out direct after the match.”
Van Gaal has been analysing footage of the defeat while most of his players have been away on international duty.
He says everyone at the club — right down to cook Mike Donnelly — must take responsibility for the defeat.
“It is not only the players,” Van Gaal added.
“It is also the staff and all the members of the staff and also my cook Mike because he has a big influence in the atmosphere in the canteen.
“A lot of people are always important in this.
“We cannot accept it from each other because we want to be the champions so then you have to behave like a champion and also to improve yourself, to be in the future the champion so you have to improve every time.”
The good news for Van Gaal is that most of his players have returned from international duty without injury.
Wayne Rooney and Michael Carrick missed England’s games against Estonia and Lithuania due to ankle and groin problems respectively, but both are fit to feature at Goodison Park.
Ashley Young is out with a calf problem, but Bastian Schweinsteiger is fit despite missing Germany’s last two internationals with a back complaint. The only major injury is to Paddy McNair, who damaged his liver during Northern Ireland’s final Euro 2016 qualifier in Finland. The centre-back is out for a month.
Those who have returned fit are ready to right the wrongs of the Arsenal performance, according to Van Gaal.
”Of course I am confident because I have seen the training sessions. I have seen the reaction of my players, so I am confident,” he said.
Van Gaal has offered words of comfort to Daley Blind and Memphis Depay after their chastening week with Holland, who failed to qualify for the European Championship.
“The main aspect of my philosophy is the total human being principle so I have to see how they come back from that defeat of course,” he said.
“I have to make a decision, it’s not easy.”
Given that Van Gaal led Holland to third in the World Cup last year, their failure to qualify for France 2016 came as a huge shock.
The 64-year-old was unwilling to speculate on why the Dutch, managed by his former Ajax player Danny Blind, had flopped.
“It’s disappointing, of course, but I can’t judge,” Van Gaal said.
Everton have beaten United on the Red Devils’ last three visits to Goodison Park, including a 3-0 victory over Louis van Gaal’s side in April.
It was the stand-out result of a late-season resurgence that helped Everton finish 11th in the Premier League table.
Roberto Martinez’s side have picked up where they left off at the start of this campaign and sit seventh going into the weekend, three points below third-placed United.
The Everton boss said: “I think the records and the previous performances and results mean very little. I think what’s important is we respect immensely this Manchester United side.
“A couple of weeks back when they hit top spot in the league, in a way that was a real statement of intent.
“We’ve got another top team coming to Goodison but we want to perform well and be as good as we can to try to get a win. Whoever we face at Goodison, we should be pushing ourselves.”