Cubase 8: Every single plugin has disappeared!

Incredibly weird issue happening here. It was working just fine earlier today, but upon starting up Cubase now I was met with a “VST sound library not found”-message which asked me to locate the FCP_SMT_001_Cubase.vstsound file, with the options “locate”, “ignore” and “remove”. Clicking “locate” and selecting the file did nothing, and the message kept appearing. Clicking “ignore” made me able to open the project, but here I was met with a message telling me all the plugins are missing (the plug-in "insert sample here could not be found for Instrument Track insert sample here). So all sample libraries via Kontakt, all paths to plugins, and every stock plugin is missing. It’s even lost all “recent projects”. It’s like it’s reinstalled itself and even forgot adding its own stock plugins. I at last tried clicking “remove” as I’ve read that solving the problem for single missing plugins, and it let me open the project, but I was met with the same result. I don’t think I got that message because of one lost plugin, but as a biproduct of everything being gone.

I’ve tried updating the eLicenser, as well as performing maintenance and registered all eLicensers, which was recommended from what I read about it, but to no avail. Is this a known problem? How would I go about solving this?

EDIT: I tried to re-add all paths in the Plug-in Manager, but once I exited and opened Cubase, they were all gone yet again. It only remembers four of the paths. Everything not located there is gone.

A similar thing happened to me today. After months of working flawlessly (until yesterday), I get numerous vst sounds libraries missing. There has been no Windows 10 updates since yesterday and there are so many lost libraries that I cannot even get to my projects. Like Khin, I performed maintenance tasks on the ELicenser. I lost several vst instruments as well, like the guitar harmonics and the Glockenspiel. I had to reinstall these through My Steinberg. What has caused this, I wonder, and how do I fix it? I am dead in the water…assistance from the pros, please!

Following up on my last post, I fixed the problem but in a laborious way and without finding the cause.

First, I had to dig into the C drive directory structure to find the Steinberg ‘‘content’’ directory. In the next subdirectory level, I found Halion. I found the vst sounds in the ‘‘vst sounds’’ directory under Halion…quite logical. BUT, for some reason, Cubase had created another ‘‘vst sounds’’ directory at the same level as the Halion directory. Cubase was pointing to it but it was empty.

My clumsy fix was to copy all the vst sounds and duplicate them in the empty directory, thus doubling the space used on the hard disc. Not very efficient but at least I can work now.

If someone could tell me how to identify which directory Cubase points to for Halion vst sounds, I could delete the directory which is not in use.

Thank you.