No sound on apps for I phone

[ledkr]

Hi. I have purchased two apps now which should have sound. One was the Davina McCall fitness app free didn't play now the upgrade doesn't and a times table app for dd which even asks you to select a male or female voice but is silent.
Any suggestions?
All other sound is fine. The Davina one even eats you select from my play lists and plays them fine when I do. I can see her lips moving but no sound.

[LegoAcupuncture]

Have you tried deleting them then readding them. Works on my ipad if I have problems with apps.

[ExitPursuedByABear]

I lost all sound on my iphone, restored factory settings and it was sorted, although I had to reset ringtone etc.

[BertieBotts]

Have you set your media volume to zero by mistake? Try going into the settings and looking at all of the different volume levels.

[BertieBotts]

Oh no that makes no sense if some parts are working I have no idea!

[DearPrudence]

Have you tried switching it fully off and on again (I know, it's a cliche but only because it often works!)

[ledkr]

Did all the above! No change. Not sure what it is maybe they download in the wrong format?
Any other knowledge?