Sound but no VOICE

Impossible to know much since you haven't provided any info on the actual audio sources and how they are used in the comp. As Rick already pointed out, there are severe limitations in dealing with audio in AE and you may simply need to prepare your files differently. More info is definitely required.

Mylenium

We need to see a screenshot of your comp with the modified properties of the layers that are giving you problems revealed and the waveforms of all layers that have sound. Select the layers with problems, press UU, then press Shift + LL. You should see waveforms and modified properties for all layers. Take a screenshot of the entire UI and embed it in the reply field on the forum. 

No workflow details, no screenshot = nothing but a guess that you have turned off the audio or changed the level on the track that is not showing up. 

One more thing. AE is not a video editing app. It is an Effects and animation app designed to create shots that you cannot create in an NLE. Most of your comps should be no longer than a single shot or short sequence. Mine average under seven seconds.

* The "Drag & Drop here..." area is buggy and should not be used to share images. Please use the toolbar or just drag your images to the reply field.