Linked Block Missing File

I’ve been quite comfortable using blocks for a while but am sure I don’t use them in the most proficient way. Recently I have started inserting building elevations and to model each in, which I then insert into an assembly file (as per a Simply Rhino video tutorial).
However when connecting these files together many, many layer stack up and are only deleted if purged and then reopened.
But whilst carrying this out somehow one of my linked (inserted) files has had the contents deleted, erasing all the roofscape and walls with rooflights etc.
This took a looong time to create. But why has the file been lost?
I’ve tried reverting to previous versions but they skip back 4 hours even though I save the file with my left hand every minute unconsciously…

How do I recover this work please?

Thanks

Hi Ned - if you open the file independently, the contents are gone?

-Pascal

It just happened again in the same situation, when exiting the block. This time I closed the file without saving but when reopening the file it didn’t open to last save I had made prior to closing (5 mins beforehand) it has reloaded the file from 3 hours ago when it was first opened today. This is a bit of a nightmare.

Hi Pascal, in answer to that time, yes, when I opened the file the contents were not showing , they were somehow embedded in the block I was editing at the time so I had to export the block to another document and then copy it back in.
Another thing to note is that not all the elements were in there, 3 layers (with blocks) were missing and had to be copied across from a previous file. (I start a new file each day I’m working on it just in case things like this happen).

Is there anything I can do to minimise this risk?

I’ve just read this,
https://wiki.mcneel.com/rhino/mac/autosaving

It seems when exiting the file and instead of saving, the other option is Revert, which reverts to the original contents of the file when opening.
So I assume the only option is to follow this:
File > Revert To > Browse All Versions…
and choose a previous save point