I have been experiencing a problem losing emails. from my inbox and my
sub-folders, many of which are from my business clients, that require a
response from me. this is posing a serious problem for me.

I don't know where to begin to look to correct this problem. my question is,
what would cause this problem and how can it be corrected ?

Is there a way to automatically backup my emails so my mail can be
recovered if necessary ?