Do you mean the new tab page that usually appears when you click the "+" button on the tab bar or press Ctrl+t?

What appears instead?

There is a hidden setting for new tabs:

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box above the list, type or paste newtab and pause while the list is filtered

(3) Double-click the browser.newtab.url preference and enter your preferred page:

• Page thumbnails (default) => about:newtab
• Blank tab => about:blank
• Built-in Firefox home page => about:home
• Any other page => full URL to the page

Press Ctrl+t to open a new tab and verify that it worked. Fixed?

Some gotchas:

If Firefox won't let you edit this setting: you may have something called SearchProtect on your system.

If Firefox lets you save your change but ignores it: one of your extensions may be overriding it. You can review, disable, and/or remove extensions on the add-ons page:

"3-bar" menu button (or Tools menu) > Add-ons > in the left column click Extensions

If the change works during your session, but at the next startup is back to an unwanted page: you might have a user.js file in your personal Firefox settings folder (your Firefox profile folder). This article describes how to track down and remove the file: How to fix preferences that won't save.

Any luck?

Your System Details list doesn't show a modified browser.newtab.url pref, so if you are talking about the about:newtab page then check if you see a grid icon in the top right corner to enable to new tab page.

If you mean the Most Visited item on the Bookmarks Toolbar then you can reset the browser.places.smartBookmarksVersion pref via the right-click context menu to 0 and close and restart Firefox.

• https://support.mozilla.org/kb/restore-default-smart-bookmarks-folders

Note that your System Details list shows that you have a user.js file in the profile folder to initialize prefs each time Firefox starts.

The user.js file is only present if you or other software has created this file and normally it wouldn't be there. You can check its content with a plain text editor (right-click: Open with) if you didn't create this file yourself.

The user.js file is read each time Firefox is started and initializes preferences to the value specified in this file, so preferences set via user.js can only be changed temporarily for the current session.

You can use this button to go to the currently used Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Preferences_not_saved

Thank you so much kind sir, about:config !!! worked very well every thing lost is now found my most visited thingy is back, I really appreciate your help, I finally have my whole browser back.