Do you means the bookmarks are gone on your Windows 8.1 system -- data loss issue -- or your desktop bookmarks are not showing up in Firefox for Android -- Sync issue?

The bookmarks aren't showing up on my desktop or on android sync.

On the desktop side, if all bookmarks are gone, try restoring a backup. Firefox usually create a backup every day or so if you make frequent changes. This article has the steps:

Restore bookmarks from backup or move them to another computer

Can you get your bookmarks back that way? Sync then should pick them up from there.

I tried that. It's like the account was created today. There is no restore point. Maybe it's because it's a work computer that the backups were not saved.

By Restore Point do you mean Windows Restore Point? Please don't use System Restore yet because it may destroy other copies of your data.

Did your desktop Firefox perform a Refresh? The telltale sign is a folder on the Desktop named Old Firefox Data which would have freshly updated files inside. If you do have such a folder, drill down into the bookmarkbackups folder to check for a recent .jsonlz4 file. Those can't be opened directly, but using the above article as a reference, you could load it using the Choose File option at the bottom of the Restore menu.

If you mean it's like the Windows account was created today, please try shutting down Windows and starting it back up again. Sometimes after system updates Firefox gets incomplete privileges that cause problems accessing settings files.