If an app is running but its window seems to have disappeared after you unplugged an external monitor, the window may still be associated with another display position or Space. Start by activating the app with Command-Tab, then use its Window menu, Mission Control, or macOS window tiling commands to move and resize the window onto the visible desktop.
This is usually a window-position problem, not lost app data. Avoid resetting the whole app or deleting preferences until you have tried the display and window-management tools built into macOS.
Confirm the app is open and the window is not simply minimized
Press Command-Tab to activate the app. Check its Window menu for the missing document or window. If the app shows a dot in the Dock but has no visible window, choose the relevant window name from that menu if available.
Also check the Dock for a minimized window. A minimized document can look like an off-screen problem when it is simply sitting in the Dock or minimized into the app icon depending on your settings.
Use Mission Control to find a window on another Space
Open Mission Control with Control-Up Arrow or your configured trackpad gesture. macOS shows open windows and the Spaces bar, which can reveal a window that was left on a different desktop or full-screen Space.
If you find it on another Space, switch to that Space or drag the window to the desktop you want. This is especially useful if the external monitor had separate Spaces enabled.
Reconnect the monitor temporarily if the window still will not appear
If the missing window was saved on a display that macOS remembers, reconnecting that display can be the fastest recovery. Once the window reappears, drag it completely onto the built-in or primary display, then disconnect the monitor again.
Do not leave the window straddling the edge of two displays before disconnecting. Put the entire title bar on the display that will remain connected.
Check Displays after changing your monitor setup
Open System Settings > Displays and verify which screens are active and whether the desktop is extended or mirrored. Apple lets you choose how each connected display is used. A changed arrangement can make the pointer and windows appear to move in an unexpected direction.
If you regularly switch between a desk monitor and a laptop-only setup, keep a simple arrangement and avoid unnecessary display permutations that make saved window positions harder to predict.
Quit and reopen the app before resetting preferences
After moving or changing the display arrangement, quit the affected app with Command-Q and reopen it. Many apps save a new last-window position when they close normally.
If the problem affects only one app and returns after every launch, the app may be restoring a bad saved window state. Check the app’s own window-layout or workspace reset command before deleting preference files manually.
Why deleting preferences should be a late step
Preference files can contain much more than window coordinates: toolbar choices, recent settings, account behavior and app-specific configuration. Removing them to fix a single missing window can create extra work or data loss in poorly designed apps.
Use preference reset only when the app vendor documents it or when you have confirmed the issue is app-specific and have a backup of settings you care about.
Prevent the problem when unplugging displays
Before disconnecting a monitor, move important document windows back to the display that will remain. Exit full-screen modes and close transient dialogs. For apps with complex workspaces, save a workspace preset if the app supports it.
If you use multiple Spaces, learn which apps are assigned to a particular desktop. A window that consistently “disappears” may actually be opening exactly where macOS or the app was told to put it.
Related guides
Frequently asked questions
What is the fastest way to look for a missing Mac window?
Activate the app, open Mission Control and check both visible windows and the Spaces bar.
Can macOS move a window back onto the visible screen?
Often yes. The Window menu and the green window button provide Move & Resize, fill, center or tiling options in current macOS versions.
Should I delete the app preferences immediately?
No. Try Mission Control, window commands, display settings, reconnecting the monitor and a normal app restart first.
Why can this happen after unplugging a monitor?
Apps and macOS can remember window positions, display arrangements and Spaces. A saved position may no longer match the monitor layout you are currently using.