Sorry to hear about that. First, is the Bookmarks Toolbar displayed?

You can use one of these methods to show the toolbar list and select Bookmarks Toolbar there:

• right-click a blank spot on the tab bar (or the "+" button)
• tap the Alt key to activate the classic menu bar > View > Toolbars
• in Customize mode > Show/Hide Toolbars (see: Customize Firefox controls, buttons and toolbars)

Any improvement?

If the bar is missing some or all of its previous contents, can you use the Library dialog to see whether they ended up in an unexpected location. To open the Library dialog, you can use either:

• Ctrl+Shift+b
• "Show All Bookmarks" from the toolbar button

In the left column, click Bookmarks Toolbar to explore whether some folders might have become nested in one another. You can drag them out if needed.

In the left column, click Bookmarks Menu and see whether there is a Bookmarks Toolbar or Personal Toolbar folder there with the missing bookmark folders.

Any luck?

If you drill down to the following folder, it should contain your profile(s):

drive:\Users\username\AppData\Roaming\Mozilla\Firefox\Profiles

You may need to unhide Windows hidden files and folders: Show hidden Microsoft files

If you find more than one folder, try the one with the most recent modification date and look inside for a bookmark backups folder. Here you should find individual .json files with dates embedded in the file names. Copy the most recent to a more convenient location such as your Documents folder. Then you can use the steps in the following article to restore that to your new installation of Firefox:

Restoring bookmark back-ups or moving them to another PC

Remember that the restore process will completely replace whatever you have in your new Firefox profile settings. If you need to preserve new bookmarks that you've saved, then you can use the export/import process as described -

Exporting Firefox bookmarks

Importing Firefox bookmarks

Thank you very much!