Ensure that Firefox is not in fullscreen mode.
If it is, press F11 to exit fullscreen.

Please report back soon.

It comes back briefly if I toggle F11 on and then off. But goes away shortly after that.

As I said - I have visited Mozilla support sites that have dealt with the problem, and have followed all instructions thereon.

Just wondered if there might be another reason this happened. It happened suddenly this afternoon, and I don't know what I might have done to trigger this response.

Is your task bar on the Windows operating system set to always be on top?

When I go to Taskbar and Start Menu Properties on the control panel, the box that comes up doesn't have the place to click "Taskbar always on top" or "Keep on top" or whatever. Sending along a screen cap of the dialog box.

I think your task bar setting is okay: it is not set to auto-hide.

Can you pull up the bottom of the Firefox window to above the task bar using this keyboard-based method:

While Firefox is active, press Alt+Spacebar to activate the window control menu. Press s to select Size, then down arrow once to select the bottom border, then up arrow repeatedly until the window clears the Task Bar, then press Enter to finish.

If Size is not available, your window may be maximized. Since you can't resize a maximized window, you may need to use the next method...

Here's the part about the RDF file: Sometimes the file that stores the positions and sizes of windows becomes corrupted. You can rename the file, but a side effect is that your toolbar customizations will be lost, as they are stored in the same file. If you want to try it:

Open your current Firefox settings (AKA Firefox profile) folder using

Help > Troubleshooting Information > "Show Folder" button

Leaving that folder open, switch back to Firefox and Exit

Pause while Firefox finishes its cleanup, then rename localstore.rdf to something like localstore.old

Restart Firefox. You should have default windows sizes and positions.

Actually, if you used the Firefox Reset feature, then in effect you've already gotten rid of the localstore.rdf file once. Did it help at least temporarily?

A user in another thread reported that the Windows magnifier could cause this problem of Firefox's window becoming too big. Do you use that feature? Perhaps there an alternative approach within Firefox to make pages more readable that would avoid this problem.

Tonight, I've got the task bar. Maybe it just needed to sit overnight and all day? Maybe it's obstinate when it's tired... like I am! LOL

Thanks!

Just see the option in your Image... 1> Start menu & Taskbar properties 2> UNCHECK the option- LOCK THE TASKBAR... Reply if not solved...

Thank you, thank you. F11 brought back taskbar. Yaay!!