Make sure the tab bar is enabled. Right-click on an empty area of the tab bar (where your tabs are) and ensure that "Tab Bar" is checked. If it's not, click on it to enable it.

   You can open a new tab using keyboard shortcuts:
       Windows/Linux: Press Ctrl + T
       Mac: Press Command + T

   You can customize the Firefox toolbar to add the new tab button back:
       Click on the menu button (three horizontal lines) in the top right corner.
       Select More Tools > Customize Toolbar.
       Look for the "New Tab" button in the customization panel and drag it to your toolbar if it's available.

   If Firefox is in full-screen mode, the tab bar may be hidden. Press F11 (or Command + Control + F on Mac) to toggle full-screen mode and see if the tab bar reappears.

   Sometimes, simply restarting Firefox can resolve display issues. Close Firefox completely and then reopen it.

   Ensure that you are using the latest version of Firefox. Go to the menu button, select Help, and then About Firefox to check for updates.

   If the issue persists, you can reset Firefox to its default settings. This will remove extensions and custom settings but keep your bookmarks and passwords:
       Go to Help > Troubleshooting Information and click on Refresh Firefox.

   Some extensions can interfere with the appearance of the tab bar. Disable any extensions you have installed and see if the new tab button reappears.

   If none of the above steps work, consider uninstalling and then reinstalling Firefox. Make sure to back up your bookmarks and any important data before doing this.

'''1. Check the Tab Bar:''' Make sure the tab bar is enabled. Right-click on an empty area of the tab bar (where your tabs are) and ensure that "Tab Bar" is checked. If it's not, click on it to enable it. '''2. Use Keyboard Shortcuts:''' You can open a new tab using keyboard shortcuts: Windows/Linux: Press Ctrl + T Mac: Press Command + T '''3. Customize the Toolbar:''' You can customize the Firefox toolbar to add the new tab button back: Click on the menu button (three horizontal lines) in the top right corner. Select More Tools > Customize Toolbar. Look for the "New Tab" button in the customization panel and drag it to your toolbar if it's available. '''4. Check for Full-Screen Mode:''' If Firefox is in full-screen mode, the tab bar may be hidden. Press F11 (or Command + Control + F on Mac) to toggle full-screen mode and see if the tab bar reappears. '''5. Restart Firefox:''' Sometimes, simply restarting Firefox can resolve display issues. Close Firefox completely and then reopen it. '''6. Check for Updates:''' Ensure that you are using the latest version of Firefox. Go to the menu button, select Help, and then About Firefox to check for updates. '''7. Reset Firefox:''' If the issue persists, you can reset Firefox to its default settings. This will remove extensions and custom settings but keep your bookmarks and passwords: Go to Help > Troubleshooting Information and click on Refresh Firefox. '''8. Check for Extensions:''' Some extensions can interfere with the appearance of the tab bar. Disable any extensions you have installed and see if the new tab button reappears. '''9. Reinstall Firefox:''' If none of the above steps work, consider uninstalling and then reinstalling Firefox. Make sure to back up your bookmarks and any important data before doing this.