paid £7.99 for app pro cant play music files greyed out any advice please. does anyone know an app or media player that plays both please.

The current version of inFuse is only a Video player (which is what it describes itself as in the App Store).

There has been talk about extending its capabilities to handle other media types (.e.g. Music files, photographs), but at the moment this is not a committed development, let alone have any ETA.