I am fairly new to Solidworks but know basics of it (basic only). The have made a shape (which I have 3D printed as well), but I need to change the dimension of the protrusion now. Here is the design
The problem is when I enter into sketch mode as shown in the bottom right corner above, the protrusion of which I am interested in changing the depth, completely disappears. I designed this a while ago so I am not exactly sure if I cut this part out or added this as protrusion. I want to fix it but I don't know how? I do not want to create the drawing from scratch, I just want to edit this one. Any help would be appreciated. Below is where you can see the protrosion completely disappears. Is there a way to combine them or is there any way to change the dimension of the protrusion? What have done wrong here?