you may also want to check for "other server" Add-ons; one of them might be the one you're looking for, or have that in it. If you find a normal folder with "[Addon name] .cs", delete it, it's an unzipped version of the Add-On (or it's functions). If none of this works, you could either just disable the Add-on, or re-download Blockand, as I have nothing more to tell you.
Please note that "[Addon name]" is not the actual name of the file/files you may be looking for, but an indicator of a name of whatever Add-On it is you're looking for.