Default Help audio files disappears

my sister records her session & keeps it as reference when she needs them. However, she was listening to some of them last night > went to bed but when she woke up to day in order to continue the recording it was all gone for no reason over 12 recordings each over 2hrs was just wiped out and could be found anymore on the device storage and shes really crying right now as her exams are on the way. Running stock 4.3 ROM not rooted or anything . Yet shes getting a lot of that crashes of Google search , etc.
GT-I9500 " after a crash and report it stated " Some of your Misc files were deleted"