I'm not sure what you mean by "it vanished"... Are you telling us the icon to start klipper is gone? Has the binary file been lost from your system?
To find out if you still have the binary file, open a console, and type 'klipper' ( without quotes ). If you still have the binary, the program should launch. If it does not launch, then do a 'locate klipper' at the command line. If the system complains the DB is over 8 days old, then log as root, and run 'updatedb' then logout to a regular user and try 'locate klipper' again.
If the icon has disappeared, you can recreate one by right clicking on the desktop, --> Create New --> Link to an Application.
In KDE it is also possible to add klipper to your task bar, by a right click on an empty part of the bar, Add to Panel, Applet, Klipper.