The Reset Firefox feature can fix many issues by restoring Firefox to its factory default state while saving your essential information. Note: This will cause you to lose any Extensions, Open websites, and some Preferences.

To Reset Firefox do the following:

1. Go to Firefox > Help > Troubleshooting Information.
2. Click the "Reset Firefox" button.
3. Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish.
4. Firefox will open with all factory defaults applied.

Further information can be found in the Refresh Firefox - reset add-ons and settings article.

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Make sure that you do not run Firefox in full screen mode (press F11 or Fn + F11 to toggle; Mac: command+Shift+F).

• https://support.mozilla.org/kb/how-to-use-full-screen

See also:

• https://support.mozilla.org/kb/Menu+bar+is+missing
• https://support.mozilla.org/kb/how-do-i-get-firefox-button

• https://support.mozilla.org/kb/How+to+customize+the+toolbar
• https://support.mozilla.org/kb/Back+and+forward+or+other+toolbar+items+are+missing

You can see which dictionary is selected if you right-click in a text area and open the Languages submenu. At least one dictionary should be installed and have a check mark to indicate that it is selected.

• Open the "Add Dictionaries" link to install a dictionary if you do not have one.
• Make sure that [X] "Check Spelling" in the right-click context menu is check-marked.

You can enable or disable spell checking globally:

• Tools > Options > Advanced : General: Browsing: "Check my spelling as I type"

You can look here for dictionaries:

• https://addons.mozilla.org/firefox/language-tools/

• https://support.mozilla.org/kb/Using+the+spell+checker