This is what worked for my issue of the notepad opening too big for the screen I was using and couldn't get to top bar to drag or the edges to resize:
Run: regedit.exe
Go to the following key HKEY_CURRENT_USER\SOFTWARE\Microsoft\Notepad . Remove the following 32-bit DWORD values: iWindowPosDX, iWindowPosDY, iWindowPosX, iWindowPosY. Now, start Notepad. It will revert to its default window size and position.