Where do LO Writer corrupt files end up?

Hi All,
first time poster, which as you can probably guess means there’s been a problem.
Have lost a thesis file today - so dramatic results… = HELP!!
Had autosave switched on
Had backup switched on
using LO v on Mac Yosemite on Macbook Air.
Have trawled through backup files in Applications folder
had a bunch of LO files open when clicked ‘yes’ to LO prompted update.
the update didn’t go smoothly, twice, which was very unusual.
End result, file lost somewhere. Maybe after ‘file recovery’ stage.

Q. How do I find it?

Q. Is it recoverable?

Q. Where do unrecovered files live?

Q. Any other tips?

Many thanks for your time