Check the C:\BB\Data\Installers folder. (replace C: with whatever drive you have the BiaB files on)

Maybe try running the file pgdx_plug_2_0_0.exe
This is the DX FX installer .. if they are truly missing this may make them reappear.
I've had to do this before, but only because someone accidentally removed them.

DX plugins are registered with the operating system, so the Run as Administrator option may be needed (right click the file and Run as Administrator)

Just an idea so you know they are installed.

I do not work here, but the benefits are still awesome
Make your sound your own!