Filling a corner

Somehow I have managed to mess up the corner of wall of my house. The left side of the image shows what it currently looks like, and the right side shows more or less what it should look like.

I tried a simple "Grid Fill", but I guess that is not what I need.

Could somebody tell me how he would fix this? I was thinking that I could perhaps use the remaining 2 faces on the bottom of the corner, but I am not sure.

• You can use those 2 vertices in the bottom. Just turn on Snap during transform with Shift+Tab, set it in Vertex mode, select vertices and extrude along Z. Then you can use Alt + F or something like that to fill faces – Mr Zak Jun 30 '15 at 13:00
• Unfortunately the vertices are not placed exactly on the grid, so the snapping does not work. – tmighty Jun 30 '15 at 13:48
• It will, if you select snap to Vertex. You can see my answer for more info – Mr Zak Jun 30 '15 at 13:53
• Ah, sorry, I misunderstood how it works. I thought I had to press Shift+Tab at the beginning of the extrusion procedure. I did not understand that I had to extrude and when the extrusion is near to where I want it, I THEN have to press Shift+Tab. Now it works great! Thank you. – tmighty Jun 30 '15 at 13:58

Select those two vertices in the bottom. Turn on vertex snapping with Shift + Tab and selecting Vertex.
Use E > Z to extrude along Z, and hover your mouse over adjacent vertices of the mesh:
• @brasshat and that's another thing I didn't think of. Btw it can be done very simple by Ctrl+Shift+Alt+M, or typing 'Select non-manifold'. So there were so many corrections to the answer that I feel I should rewrite it – Mr Zak Jun 30 '15 at 20:11