You might have clicked tab button by mistake and the UI disappeared. To bring it back, you can press tab button again. If it doesn't work, you can try the following steps:
- Select
Show Toolbarin theViewmenu. - Select
Show Toolsin theViewmenu. - Select
Show Context Toolbarin theViewmenu. - Uncheck
Hide Studioin theWindow -> Studiomenu.
There you go! Your Affinity UI should be back to normal.
