What operating system are you on?
Your post is not clear about what your workflow was. But it sounds as if the trip from LR to Silver Efex worked as expected (you say that you "got the photo back") You then sent it to Photoshop - presumably via the Edit In command. What is not clear is what happened after that. You say you printed it - from Photoshop? But then you say you added it to a collection and added keywords. You could only have done that in Lightroom - was that before or after you sent it to Photoshop?
Have you checked the folder where the original file was saved? I have been plagued for over a year now with the round trip to Photoshop not showing the saved photo from Photoshop in the Library Module - although it is properly saved in the original file's folder (I am on Mac OSX - various versions and now 10.14.6). Endless sessions with Adobe Support have failed to explain what is happening or why let alone to find a solution. Quitting LR and restarting then brings the photo into the library module but not a collection.
Check the original folder and see if it is there.
Sorry for not being clear and for the late reply, I guess I assumed I'd get an e-mail if anyone replied.
Yes you fully "guessed" my workflow by carefully reading my somewhat terse message :-)
Import RAW to LR.
Edit in Silver Efex Pro : and for the first time I clicked the button that should make it possible to reopen the file in Silver Efex for later editing.
Back in LR: "Edit in Photoshop" mainly to print.
Save back to LR.
In LR add to by Hahnemühle collection and add keywords about paper, use ABW, etc.
And then, seriously no idea what happened. I normally wouldn't accidentally delete a photo.
I searched my PC 'including the Lightroom foldder) for the file name (without extension) but could not find the one with the "B&W" keywords.
I did start editing some virtual copies (one of which went back and forth from DXO Photolab 3) because I like the colour versions as well.
From what I read Silver Efex (from DXO Nik Collection 3) somehow embeds the photo within the original copy that LR sends it.
It's not a big issue since I did not ddo any heavy editing in Silver Efex: I normally start using the film emulations and the do some slight edits on top of that.
So I can redo it without any problem.
I'll have to do some testing to see if I can reproduce the issue.
As of now it seems logical that I accidentally deleted it but LR asks for confirmation and I can't see how I could do that.
Best regards,
Frank