That folder was truly erased (bypassing the recycle bin). Unless you created a backup on local media or in the cloud, your best hope is to use software that combs your hard drive for fragments of files to "undelete" them.

For example: http://www.piriform.com/recuva

This should be done immediately, as that space will gradually be overwritten, corrupting any recovered files.

When you find the list of recovered files, look for ones whose names start with "bookmarks".

More specifically, you are looking for files with names like:

bookmarks-2014-03-25_4678.json

These can be restored to a new installation of Firefox is they are not corrupted. See: Restore bookmarks from backup or move them to another computer.

If they are corrupted, and not repairable, you could go through them in a text editor and pull out the URLs.

Note that current Firefox releases include the number of bookmarks in a JSON backup file ass part of the file name (xxxx in bookmarks-####-##-##_xxxx.json), so you can't search for a specific name, only for a pattern.

You need to check the content of the recovered files to make sure that those files are valid JSON files and do not have cluster data that has been reused to store data from other files.

• JSON Formatter & Validator: http://jsonformatter.curiousconcept.com/
• JSONLint - The JSON Validator: http://jsonlint.com/