No sound on some apps despite "sounds" being enabled ...help appreciated. iPad 1

Have you got notifications muted ? Only notifications (including games) get muted, so the Music and Videos apps, and headphones, still get sound.

Depending on what you've got Settings > General > Use Side Switch To set to (mute or rotation lock), then you can mute notifications by the switch on the right hand side of the iPad, or via the taskbar : double-click the home button; slide from the left; and it's the icon far left; press home again to exit the taskbar. The function that isn't on the side switch is set via the taskbar instead : http://support.apple.com/kb/HT4085

Thank-You soooo much for your help in discovering why my apps, games & keyboard clicks were not working. My music & videos were fine, so for the life of me I could not figure out what was going on. You corrected my problem. Somehow that sound icon was switched off.It was a simple fix. Thanks again Kathy B.