I accidentally deleted a file
Basically a deleted file cannot be recovered.
However…
-1- If you have enabled >Tools>OPtions>LibreOffice>Load/Save>>Save>>>Always create a backup copy you shoukdfind a copy of the previous state (before last editing) of the file in tzhe backup folder of your user profile.
-2- You may search your system’s trash directories for recoverable deleted files.
-3- Operating systems mostly don’t physically delete files immediately, but only mark the used storage space as free for overwriting. Files that were not yet overwritten can sometimes be recovered the using special software lice “Recuva” e.g. on Windows. This is not a recommendatiuon, but a mentioning. Not having used such tools for years I cannot give a recommendation.
Anyway: As long as you are hoping for recovery, you should use your computer as little as possible to avoid accidental overwriting by the system. Find the recovery software you want to use (portable, on a stick) and apply it.