This is just a quick guide to explain how to restore your bookmarks that have gone missing in Firefox. If you have any question just post or PM me.
Why does it happen?
Well first of all, in Firefox some people have their profiles randomly go missing. This is caused by the Firefox.exe hanging, then the user opening another Firefox window.
They then get a message box asking them for a name for their new profile. Not realizing this is going to override their old profile they type a name then hit OK.
When they get back in to Firefox, they see that all their settings have returned to the default (Theme selection, bookmarks, etc.).
How do I restore my bookmarks?
The profile is easy to restore luckily.
First of all, close Firefox.
Now browse to C:\documents and settings\your windows username\application data\mozilla\firefox\profiles\
Now you will probably see 2 or more profile folders.
One of these will be your old profile and one will be your new one.
Pick a profile folder and double click it. You will find a file called bookmarks.html (Ignore bookmarks.bak).
Open this file with Notepad, Firefox, or any other browser or editor of your choice.
If the File contains the links that you used to have in your bookmarks then you've now found your old bookmarks file.
Now to restore there are 2 methods:
1. Right click the file you found and click copy -> Browse back to the profiles folder (C:\documents and settings\your windows username\application data\mozilla\firefox\profiles\) -> Double click the other profile folder -> Right click any white area -> Click "Paste"
2. If you've already started adding some new bookmarks to your bookmarks menu in Firefox and don't want to lose them, but want to import your old bookmarks:
Open up firefox -> Click Bookmarks -> Manage Bookmarks -> Click File>Import -> Choose "From File" -> Click Next -> Browse to that Bookmarks.html file we found -> Open.
I hope this helps you out and if you have any questions, or suggestions of better ways to import your bookmarks.html file, PM me or post here.