This file appears to be difficult to get a hold of for whatever reason. It allows you to extract files that’re packaged together into a texture pack (for texmod / umod) to be extracted back into dds/ddo files.
However the original site(s) that hosted this file, and opentpf appear to have gone. Not even existing on the web archive (some of the sites are purposefully excluded from the web archive).
TPFextract is most usable with TPFextractGUI.
TPFextractGUI comes with its source code. TPFextract I think, used to be on Google Code, which is now defunct/archive only.
So I’ve attached TPFextract to this blog post. TPFextractGUI is still available online.