Inversion
is the norm in questions, David. Thus we have: 'How do I use
inverted word order?' 'Have you seen my dictionary?' What is
the problem?
However,
it is normally not used with indirect questions or verbs of reporting.
So we have: 'I'd like to know how I use inverted word order.'
'I asked my flat-mate if she had borrowed my dictionary.' 'I
explained what the problem was.'
Sometimes,
inversion is used in statements to give emphasis, especially when
the statement begins with a negative word or idea:
'Under no circumstances can your money be refunded.'
'Only when I had been there for a year did I begin to feel
at home.'
'Not only did I lose all my clothes and jewellery, but
my chequebook, passport and visa card went too.'
Inversion
is, of course, necessary after neither, nor and so:
