To programmatically "maximize" a "minimized" app, call Form.Show.

The Windows Mobile shell is not like the Windows XP/Vista shell -- when you
"minimize" an application under Windows Mobile, it does not get minimized to
the task bar like with the desktop operating systems. It gets moved to the
background and continues to run. To "maxmize" a "minimized" application
under Windows Mobile, you need to do one of two things:

1. Click Start->Settings->Memory, select the Running Program tab, highlight
your app and click Activate
2. If you have a shortcut for your application in Programs, click
Start->Programs and then launch your application -- .NET CF GUI apps are
single-instance under Windows Mobile so by attempting to launch another
instance of your app, it will bring the running instance to the front, i.e.
maximize it.

If you don't have a shortcut in Programs, use File Explorer to find your app
and then re-activate it from there.