United have failed to win a major trophy since Ferguson retired at the end of the 2012-13 Premier League season, with only the 2013 Community Shield to their name.
After David Moyes' unsuccessful stint as Ferguson's successor, Van Gaal has had no further luck since taking over in 2014.
The club have endured a somewhat troubled campaign in 2015-16 and things have taken a turn for the worse in recent outings, losing at relegation-threatened Sunderland before falling to Midtjylland in the Europa League.
And as United prepare to face third-tier side Shrewsbury Town in the FA Cup, Van Gaal believes United have lost their trademark fear factor.
"When you see the last two games, it’s maybe like that," the Dutchman said. "But then we have to make them fear us again.
"We lost the first match in the Premier League also, against Swansea City, when I first came here.
"But then still we had a very good home record last season - and we can do that again. It’s a question of winning matches in a row. That I have said also already to the players, because you cannot continue with losing games.
"The question is how we lift ourselves for this game, because Shrewsbury Town shall also fight for the second balls, play direct and that kind of thing, and we have to cope with that.
"We have to keep the ball better and not give unnecessary losses away, because I think the first goal [against Midtjylland] was an unnecessary loss and the second goal we could have won that duel much easier."
