On the homescreen, hold the alt key and click the thumbwheel. If you have the option for show all, then some are hidden. If they are not hidden, then the application may not be installed and you would need to use application loader (with the handheld software installed on the computer) to install them.
For attachments, go to Options > Service Book. Make sure you have an entry that ends with [CMIME].
If you are a BIS user, send yourself new service books. If you are a BES user connect the handheld to the computer and regenerate a new encryption key.