Yeah, if you can post the block, we can fix it for you, but if not you should be able to do it. Before you modify your block, save a backup copy then get to work on it.
Open the block file, use QUICKSELECT to find the Block Reference with the Name property matching your block name (filename). See what happens when you delete it.
Then try purging everything out of the drawing and save it.
Go back into the drawing you want to update and try Ron's suggestion or my macro and see what happens.
EDIT: Too late... there's the block.