I'm presuming you can click on 'Write' and it opens ok. But, you cannot see the top 'Menu Bar' - the 'Menu Bar' toolbar offers 'File', 'Edit', 'View' etc nor the 'Composition Toolbar' which has 'Send', 'Encrypt', 'Spelling', Save'

Click on Write to open a new Write window.

• Press the 'Alt' key on keyboard to get a temporary 'Menu Bar'
• 'View' > 'Toolbars' > select 'Menu Bar' to set the Menu Bar as permanent.

Now reinstate the Composition toolbar :

• 'View' > 'Toolbars' > select 'Composition Toolbar'

If you also need to see the 'Formatting Bar':

• 'View' > 'Toolbars' > select 'Formatting Bar'

No the whole problem is I can't click on "write" because that is the tool bar that's missing.

i can receive messages & reply to them only.

                                   if I "archive" I cannot "File" the archive.

Cannot "Write" anything - this is the tool bar missing,

Can  "Archive" but cannot "File"  it because that "Dropdown menu does not appear.

click view>toolbars>Mail toolbar from main screen.

If you cannot see any Toolbars in the main Thunderbird where you see the Folder Pane.

• Press the 'Alt' key on keyboard to get a temporary 'Menu Bar'
• 'View' > 'Toolbars' > select 'Menu Bar' to set the Menu Bar as permanent.

Now reinstate the 'Mail toolbar :

   'View' > 'Toolbars' > select 'Mail Toolbar'