It is common for clients to request assistance with a opened application on the task bar. However, the client is unable to restore or maximize the application with conventional methods. The most effective step is step number 1 below.
1.If a window won’t maximize, press Shift+Ctrl and then right-click its icon on the taskbar and select Restore or Maximize, instead of double-clicking on the icon.
2.Right-click on the desktop, select Refresh and see if that helps
3.Press Win+M keys and then Win+Shift+M keys to minimize and the maximize all windows.
4.Press WinKey+Up/Down arrow key and see.
5.Press Alt+Space and see if the Maximize/Restore/Minimize, etc, box appears. If it does, use it.
6.The last step is to open Task Manager, kill the program process and start it again.