Nepal are one of 10 teams taking part in a three-week long qualifying tournament which starts in Zimbabwe on Sunday.
Only two nations will book places at the global showpiece event in India in October and November.
"Looking at the qualifiers, we believe that if we play quality cricket, we believe that we are going to win most of the matches," said Sheikh.
"It is just about playing the best cricket on the best day, so we believe that if we play our best cricket on that day, we are going to win."
Nepal, who won 11 of their 1ast 12 matches to reach the qualifier, face a stern test on Sunday when they open their campaign against hosts Zimbabwe in Harare.
In warm-up matches last week, they went down to a penultimate ball defeat to the UAE and then achieved a two-wicket victory over Oman.
Sompal Kami picked up a five-wicket haul against Oman, while Kushal Bhurtel hit a 94-ball century.
Sheikh top-scored with 76 runs in the defeat to the UAE.
Zimbabwe, who failed to qualify for the 2019 World Cup, won both of their warm-up games against Oman and Scotland.
Sikandar Raza registered an unbeaten 110 not out from 67 balls before taking three for 43.
Raza top scored again versus Scotland, with the hosts needing just 24.5 overs to eclipse the 163 posted by their opponents.
"Preparations have been excellent leading up to the tournament," said Zimbbawe skipper Craig Ervine.
"There is some really exciting cricket coming up and exciting players to watch in Sikandar Raza, Blessing Muzarabani and Sean Williams."
Two-time champions West Indies also get their Group A campaign underway on Sunday against the United States looking to maintain their ever-present record at World Cups.
A 3-0 series victory against the UAE earlier this month was then followed by victories in Harare against Scotland and a fourth win in a month against the UAE in warm-ups.
Brandon King top-scored in the UAE series, while Yannic Cariah took four wickets in each of the two warm-up games in Zimbabwe.
"I wouldn't say not qualifying would be a failure, but I wouldn't look down that road because I think we'll definitely qualify," said West Indies all-rounder Keemo Paul.
The United States have never played at a World Cup and are in the qualifier for the first time since 2005.
Warm-up matches saw defeats to Ireland and Sri Lanka although Aaron Jones showed form with 89 from 87 balls against Ireland.
"In this team, I am the person to anchor the batting so I will take pride in doing that and getting my team to the World Cup," said Jones.
"It would be great to grow the sport in our country and play in World Cups. Not only for ourselves – when we move on, we want to leave something behind for the youngsters to look up to. It is very important for us to have a legacy."
