Paul Bin, William James Herve and Brayan Padilla were sidelined for much of 2019.
The Terps circulated a picture on social media kneeling in solidarity against police brutality and racism last week.
The son of Kenyan immigrants, Ngobu played for various club teams in Maryland before coming to College Park.
The German started 18 games, and was an all-Big Ten second team selection in 2019.
Players are using toolboxes and empty fields to stay in shape instead of state-of-the-art equipment.
The Terps added two midfielders and a goalkeeper.
A 3-0 loss to Wake Forest in the NCAA tournament ended the Terps' rocky campaign.
Defenders Brett St. Martin and Ben Di Rosa picked up injuries in the Terps' win over Iona.
The Demon Deacons capitalized on their chances while the Terps failed to do the same.