Things happen that can lead to broken trust.
I just went through this with one of my birds, Phoebe. It took 20 days of trust building only , no training, to win her back . This is basically like starting over to win their trust, like you would if you just brought the bird home. Going and saying hi, with treats, many times a day. Use a treat dish if can't give treats by hand right now .
Don't force interaction. If they t used to let you pet them , you will probably have to earn back that privilege as you earn back trust .
Keep in mind , young birds might not be cage protective, but as they become adults many will protect their cage. So I prefer them to come out of cage to a perch attached on the outside of the cage by the door. Then interact with them