Depends on the toolbar. Menu Bar with File-Edit-View etc, press the Alt Key.

All others from the Menu Bar select View-Toolbars and turn them on.

it's already on. now what??

delete disappeared from customized how do i get it back

What is already on?

Send and Delete are in two different windows.

Send Is on the Composition Toolbar in a Write window and Delete is on the header of the Message Pane by default and can be placed on the Mail Toolbar in the main window using the Customize menu.

What customize? What toolbar are you trying to customize. If not the Mail toolbar you are wasting your time.

Maybe you are missing the Message Pane. Press F8 whille viewing the main window.

Now I lost the date column in Thunderbird. How do I get it back?

Help!

At the right end of the header bar is an icon. Click that and turn it back on.