You can unhide Opera with anyone of the following ways.
- Right click on Opera tray icon > Open Opera (This is not possible if Show Tray Icon is disabled).
- Click Opera shortcut in quick launch or double click Opera shortcut in desktop to restore Opera with a new tab.
- You can use the default shortcut, Ctrl+Alt+Shift+H to hide Opera but not possible to unhide with same shortcut since Opera doesn't have focus. But you can unhide Opera by defining a shortcut key to Opera shortcut in desktop (Right click on Opera shortcut in desktop > Properties > Shortcut key).
Shortcut key must be different from Opera keyboard shortcut to hide Opera.
Opera shortcut key