Some Steinberg Plugins cannot be found any more

Some of the internal Steinberg PlugIns in my Cubase 6.5 are somehow gone. I cannot load them and even the .dlls can’t be found anymore in the PlugIn Folder. It’s only some of them - the Envelope Shaper for example which I really need from time to time and the Drum Synth and the Compressor.

I did not delete them and I can’t find them in the Quarantaine folder of Avast.

Can I find the dlls somewhere to download? Any ideas what my problem could be?

Thanks a lot

Windows 10