i was working on mail and arrow with nice airplane sound disappeared and changed to the word sent how do i go back to arrow ?

View -> Customize Toolbar should allow you to re-add any missing toolbar icons.

Launch Mail.

Start "New Message".

Click "View" in the menu bar and then "Customize Tool Bar".

Customize Toolbar sheet should drop down.

At bottom left there is "Show" pop up box, click it and select "Icon and Text".

Click "Done".