I wonder if this happened to other users. I right clicked on a study on the price chart to access its properties and the chart closed. The right click menu didn't display at all. This had happened to me before so that's leaving me wondering if it is something I'm doing that caused this.
Also, is there a way to redo a close?
You might have clicked in the upper right corner (there is mini button to close the chart located there) or your mouse may have problem with microswitch (malfunction).
As for closing pane and recovering there are existing threads that cover that: https://forum.amibroker.com/search?q=pane%20closed
To always display a prompt before deleting pane you have to go to Tools->Preferences
and enable "Ask before closing indicator pane"