If your on your Samsung Galaxy S5 the new Android 5.0 Lollipop used, it may be that you, the text disappears from new WhatsApp messages on the lock screen. Instead, you only see "WhatsApp - hidden content"
This is a new feature of Android Lollipop, which allows hide contents of new SMS and WhatsApp messages on the lock screen. Thus, it is not possible that someone can read what is in a new message arrived when the smartphone is locked. If you interfere with this feature and your dear again want to have displayed on the lock screen the complete message, then you must make your following settings:
Opens on your Samsung Galaxy S5 (Also works on other Android smartphones Lollipop) the menu and then the settings. Typing on here "sounds and notifications". Now scrolls all the way down to the section "notification" and typed in there then "If disabled".
A window opens in which you select now "Show All Content" muss.Fertig!
If you now receive a new message or new WhatsApp message on your Samsung Galaxy S5, then you, the text is displayed in directly on the lock screen.