It's pretty hard to lose a file permanently in LBC because it keeps backups and multiple files.. But it's easy to misplace stuff since LBC can be confusing.
The first task is to open the options of lbc and go look at what dock files are loaded -- see if you see your dock in the OPTIONS.. If so then you know it's just a matter of configuring where it is on screen.
If its not even listed in the list of tree node files, it may just need to be OPENED by you in the options. One of the confusing things about LBC is that you can have multiple dock files loaded at the same time, so it may be that you closed one of the files (rather than just toggled off one of the docks).
See what you can figure out and let me know.