It is my understanding that doing a Security Wipe of your device will resolve this issue.
1. Be advised:
* a. If you are on a BES account, you will need to reactivate your device on the corporate BES, likely getting a new activation password from your BES Admin.
* b. You should backup your device first, using Desktop Manager, and/or sync to Outlook if you do so.
2. Then proceed:
* On your device (for OS 5.0 devices), go to Options > Security > Security Wipe and proceed.
* On OS 4.7 and lesser devices, your path will be Options > Security > General Settings > press the Menu key > Wipe Handheld.
*Do not include third party applications/user installed in the wipe, uncheck that option.
3. Uncheck the "delete applications" options in the Security Wipe.
4. Proceed with the Security Wipe.
You check afterward to see if you find the AppWorld icon, and if not, install it from your browser at BlackBerry App World
Then, using Desktop Manager > Backup/Restore > Advanced, select to restore your backup file for re-adding your messages, contacts, calendar, etc., back to your device.