You have 2 choices
You can delete the region file r.-1.0.mcr
Or
You can download NTBExplorer (http://www.minecraftforum.net/topic/840677-nbtexplorer-nbt-editor-for-windows-and-mac/) , open that region file, find the chunk -19, 16 (have to expand each chunk section until it says xPos -19, yPos...