We will do this in Object Mode, with no objects selected, with nothing else in the scene, or with the messed up object visible in it's own layer.
- Press A once or twice to deselect all objects.
- Right click one of the parts to select it.
- Then use Select>Select All By Type>Mesh
- This will select all the mesh you just imported & select it correctly for the next step.
- Finally use Object>Snap>Selection ->Cursor.
- Fixed in most if not all cases.
