The Windows 10 update has various options for what to do with your old data. Can you check for these folders to see whether and how many old profile folders you can find?

First, please turn on viewing of hidden files and folders: http://windows.microsoft.com/en-us/windows/show-hidden-files

• C:\Users\your-user-name\AppData\Roaming\Mozilla\Firefox\Profiles
  • How many profile folders do you find? If there is only one folder, it's likely your current one that doesn't have your data.

• C:\Windows.old\Users\your-user-name\AppData\Roaming\Mozilla\Firefox\Profiles
  • How many profile folders do you find? If there are folders here, one of them most likely has your latest pre-upgrade settings.

Based on what you find, we can suggest the shortest set of next steps.

These can't get your data back, but will help in the future.

These add-ons can be a great help by backing up and restoring Firefox

FEBE (Firefox Environment Backup Extension) {web link} FEBE allows you to quickly and easily backup your Firefox extensions, history, passwords, and more. In fact, it goes beyond just backing up -- It will actually rebuild your saved files individually into installable .xpi files. It will also make backups of files that you choose.

OPIE {web link} Import/Export extension preferences

So I went out for a bit and when I came back all of my bookmarks had been restored. I have no idea what happened. Now my desktop is empty though, so I have no idea what is going on with this ridiculous Windows upgrade. Thanks so much for your help. I'm going to back up all my bookmarks now!