Wie kann ich fette und kursive Schrift in InDesign sichtbar machen?

Display of the correct font and face is integral to InDesign and needs no special setting or accommodation. A corrupt document, a corrupt or incompatible font set or corrupt user settings could cause display problems, though.

First, know that InDesign does not 'synthesize' italic and bold in the way Word does. (Any font in Word can have italic, bold or bold-italic characteristics applied through type distortion; InDesign and most other professional tools require that actual italic, bold etc. fonts be installed.)

Second, does this occur in all documents, including newly created ones, or only in one or more specific documents? (If the documents were imported from Word with Word-basis overrides, as above, InDesign may not display the 'synthesized' enhancements.)

Third, does this occur only with one font/family or do other common or base fonts (such as Minion Pro) also fail to display bold and italic?

If none of these seem to apply, you may need to clear your user preferences. It varies a little by platform/OS and version, but here's a comprehensive description of how to do that and other "reset" processes:
Reset InDesign Preferences and Other Troubleshooting

Weshalb siehst du die Schriftauszeichnung nicht?

Hast du diese Schriftschnitte installiert?

Oder verwendest du False Styles?