When you use find-all and find-in-files in Notepad++ a search-result window appears below the screen. On my system this window have been hidden (possible I have dragged it to minimize) and it cannot be unhide.
I have tried to drag all bars in notepad++ window; but nothing was able to unhide it. The window is still there - somewhere in dark - and if I press F7 and enter, the first search result will be open. but the search-result window is still hidden.
My search window was un-docked and it had went out of the screen for some reason I didn't get.
This time I searched for a word, and chose Search All Opened Documents', then I pressed F7 so the cursor goes to the 'Search Window'.
Then I used the old Alt+Space, M to move that window. And it worked! it was somewhere in the middle of a non-existent screen.
As posted on a previous answer on a relevant question, have you tried this solution?
Mouse over to the top section of the status bar
The cursor will change to the vertical resize shape
Hold it using the left mouse click, and drag it upward to reveal the missing search result window
