When I minimize windows they disappear? or There are no applications in my toolbar.

gnome-panel needs to be restarted. In a terminal window, type:
pkill gnome-panel
If your toolbar doesn't restart, type:
ps -ef | grep gnome-panel
In the second column, there is a number. This is the process id (pid).
In the terminal window, type:
kill -9 
This should restart the toolbar.