This answers some of your questions, I'll have a second post about looking for your lost data.

(1) Menu Bar

You can still use the "classic" menu bar in the new interface. It's on the toolbar list with the Bookmarks Toolbar and any add-on toolbars. You can access that using any of these:

• right-click a blank area of the tab bar, or the "+" button on the tab bar
• "3-bar" menu button > Customize > Show/Hide Toolbars
• tap the Alt key to display the classic menu bar temporarily, then View > Toolbars

(2) Bookmark This Page

This is still on the Bookmarks menu on the classic menu bar. Or on the right-click menu, there is now a star icon for this. Or you can use the keyboard shortcut Ctrl+d instead.

The new star icon on the main toolbar lets you edit immediately if you double-click it instead of single-clicking it.

Hopefully this helps?

Normally, installing a new Firefox doesn't wipe out your old Firefox data. On the contrary: the installer looks for and uses that data if it is found.

To manually search for your old settings folder, I'm going to have you copy a location and then paste it into the start menu search box and press Enter. This looks weird, but it's a shortcut so I don't have to ask you to type in your Windows username:

%APPDATA%\Mozilla\Firefox\Profiles

Windows should show a folder with one or more semi-randomly named folders. Typically there is a dot in the name and at least one of the folder names ends with "default". If you only have one folder here, then your old settings folder might really be gone. If you have multiple folders here, one is your currently active folder, and one of the others may be your old settings.

Could you take a look and see? If you have additional folders, check inside to see whether you can find a folder named bookmarkbackups, and then look inside that to see whether any of the files are recent. Depending on how your Windows Explorer is set up, you might need to switch to the Details view to see the "Modified" dates for the files.

By the way, I don't know whether your son-in-law deleted any folders, but if so, they might still be in the Recycle bin. If you open the Windows Recycle bin and see any recently deleted files/folders that seem to be related to Mozilla or Firefox, or follow that strange naming pattern, you might need to restore those later.

Thanks, jscher2000. I don't know how it happened, but I now have my line at the top of the page: File, Edit, View, History, Bookmarks, Tools, Help. That is such a relief. They seem to have appeared while I was typing to say your advice hadn't worked! The only thing "wrong" now is that when I click on 'Bookmarks' I get a box with 7 choices, whereas before (I think) I got 'Bookmark this page' with all my bookmarks below. Now I have to click on 'Unsorted Bookmarks', and instead of a nice simple list of my bookmarks I get a window with the bookmarks and their Location (and Tags -- I don't know what tags are). I guess anybody starting out now would be happy, but I like the way it was before. I was used to it. It was familiar. I don't like change.

Hi Bert, you can use the Library dialog ("Show All Bookmarks" or Ctrl+Shift+b) to move the booksmarks currently in the Unsorted Bookmarks category to the Bookmarks Menu, or the Bookmarks Toolbar, as you wish. You can click and drag them.

Now when you say clicking Bookmarks gives you a box, the Bookmarks menu should operate the same way it always has. If you are clicking the combined button on the toolbar (star on the left, something like a clipboard on the right), the left part does an immediate add to Unsorted Bookmarks and the right side should show the menu. Is one of those three not working normally?

Earlier I mentioned the alternate ways to use Bookmark This Page: https://support.mozilla.org/questions/1052291#answer-704325

Hi, jscher2000 Sorry it's taken a while to get back to you, but even following your first set of advice made my brain ache! I did what you said about using 'Search' and I found only one folder with 'default' in the name. There was nothing there that was older than the date my s-i-l installed the new Firefox. Can you tell me what went wrong? Why did my computer lose or hide Firefox? What can I do to stop it happening again? I have a back-up on an external hard-drive, though I haven't backed up for a couple of months. Is there any chance my bookmarks could be on there? My s-i-l thinks not, he says the back-up only backs up pictures and documents.

When you got to the Profiles folder, was it this one:

C:\Users\username\AppData\Roaming\Firefox\Profiles

Was there only one folder inside or were there others, named something other than default? If there were others, it's worth looking in those, too.

Regarding a backup, it depends. Some backup software may try to copy all of your data, while other backup software might only get a small set of data. I think you have to take a look and see.

Note: In case you are running into the problem of not being able to drill down into hidden folders, you can make sure they are visible using the steps in this Microsoft support article: http://windows.microsoft.com/en-us/windows/show-hidden-files#show-hidden-files=windows-vista

As for what caused the original problem, I really don't know. Firefox should never delete itself. Some other software might have tampered with it, but I'm just speculating.