Restore Send icon in Apple Mail I have lost the "send" icon on my Apple mail, top right corner
How do I restore it?
Start a new message  Command ⌘ / n   , then with that message front-most [this gives different choices than if the main window is at the front]  

View menu > Customise Toolbar...
Drag the default set at the bottom into the toolbar, or just drag the Send icon back to where you'd like it.