Manchester United lost 1-0 to Newcastle United on Sunday afternoon following Matty Longstaff’s second-half goal at St James’ Park.
The Red Devils have lost three times in eight games in the Premier League, with Manchester United only having managed to beat Chelsea FC and Leicester.
Manchester United spent nearly £150m on new players in the summer as Solskjaer signed Harry Maguire, Aaron Wan-Bissaka and Daniel James.
However, the Red Devils paid the price for failing to improve their attack despite allowing Alexis Sanchez and Romelu Lukaku to leave the club.
Manchester United have scored five times in their last seven games since a 4-0 win against Chelsea FC in their season opener at Old Trafford.
Former Red Devils star Sharpe says Manchester United need to spend £300m on new players to help improve Solskjaer’s squad.
“The last three managers, and the last three ways of doing things, have all not worked,” Sharpe told talkSPORT. “So I don’t think it is just the managers.
“You’ve got to look at who is appointing the managers and who’s running the club from the top.
“This is another way of doing it, with Ole and playing youngsters and getting lads through the academy and getting rid of players like [Romelu] Lukaku and [Alexis] Sanchez and [Ander] Herrera.
“It is another avenue and they’ve got to trust what they are doing.
“Otherwise it’s another change at Christmas and it all starts from the beginning again.”
Manchester United haven’t won the Premier League title since 2013, when Sir Alex Ferguson was still in charge.
The Red Devils finished in sixth spot in the Premier League table last season.
The 20-time English champions appointed Solskjaer as their new manager after Jose Mourinho was sacked back in December.
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news