Do you remember the name of the original profile?

Type about:profiles<enter> in the address bar. Is it there?

No, I don’t remember, but the menu& bookmarks have now appeared, I don’t know why! So, all is OK now.

Is Firefox using ANY of the data from your previous profile? In other words, do you just need to turn a couple of "bars" back on, or do you also need the actual bookmarks.

As a test, you can type some of the title or URL or a bookmarked page into the address bar and see whether it shows up as a match in the autocomplete drop-down panel.

If you have the data, to show the bars

To turn different bars on and off, you can use one of these methods to show the toolbar list and select the desired bars there:

• right-click a blank spot on the tab bar (or the "+" button)
• tap the Alt key to activate the classic menu bar > View > Toolbars
• in Customize mode > Show/Hide Toolbars (see: Customize Firefox controls, buttons and toolbars)

To turn on the Menu Bar, Bookmarks Toolbar, or other bars, click it on the list.

If you do not have the data

These two need to be in sync:

%appdata%\Mozilla\Firefox\profiles.ini => profile path must match:

%appdata%\Mozilla\Firefox\Profiles\abcd1234.oldfolder

If Firefox created and is using a new profile folder, it may be persuaded to use the old profile folder either by renaming the folders so Firefox thinks the old folder is the new one, or by editing the profiles.ini file to correct the path to the old profile folder name. It sounds as though you are comfortable with file/folder operations, but let us know if you want detailed steps.