The major cause of this issue is upgrading either app without first deleting the previous version . It is not so difficult to get the solution to the problem of a missing Blackberry World (appworld) or BBM icon.
+ The first step is to show all hidden apps under applications > menu button > show all.
+ Another approach is applications > switch > check through all listed apps .
+ go to options > applications > check if the app is listed then delete
+ install a lower version of the app
... hope this helps