Is Bitcoin in the ALT-TAB list of running programs? Perhaps you can switch to it this way. Also, it's tray icon might be hidden by Windows if you have customized "Notification Area Icons" in the control panel; check the checkbox for "Always show all icons and notifications on the taskbar".
Review the file %APPDATA/Bitcoin/debug.log. It should have any error message near the bottom that will help in diagnosing your problems to see if Bitcoin has really hung or crashed. Bitcoin does take 5-30 seconds to launch though, depending on what it has to do when starting up.
More information about your situation would be helpful in the first post: have you ever had Bitcoin working, etc.