Search icon disappeared (changed into text 'fl')

Hi everyone,

The search icon in our menu bar disappeared. Instead of showing the icon, it now shows the text ‘fl’. I cannot find a reference to an image file in the stylesheet or the searchform.php code.

The search icon probably ‘disappeared’ when we dragged the wordpress directories from https://www.<websitename>.com/wp to the main domain.

Any help is welcome. Thanks in advance!