No sound suddenly

Bought iPad Air several days ago. Last night when I bought my first app, it had trouble accepting my sign in. Had to sign in at least 6 times before the purchase was processed, but it finally succeeded. Today, I went to stream some video and suddenly had no sound. Adjusted volume, nothing. Checked settings, nothing looked amiss. Checked music app, still no sound. Restarted and sound returned. Played a game, then noticed 2 other game apps were missing, including the one I bought & played yesterday. Went into purchased apps, both were showing as on the iPad, with OPEN buttons, but neither would open, although other non-affected apps would. I've just noticed that I've lost all sound again. I can try a factory reset, but am wondering if anyone can clue me in if they have ideas on what might have caused this or what is going on? Thanks.