I have a strange problem. I am doing the doughnut tutorial series, and things were going swimmingly until I some how lost part of the mesh in the UV editor. The screen shot below shows that I have a texture, and it's mapped to the object correctly, but a chunk in the middle somehow went missing or I accidentally deleted it. The renders now come out with black sections that matches the missing area in the UV edit. Is there a way to re-construct the missing mesh for UV editing ? I have tried unwrapping the mesh again, but this doesn't seem to have any affect restore a single and complete mesh.
--Update-- I've managed to select the missing mesh on the object, and attempted to unwrap it, but i can't make blender unwrap the selected mesh as 2d square.