What is the negative inversion for this sentence?
She made no sound as she crept upstairs
My Answer:
No sound did she made as she crept upstairs
Is this correct? If not, how could it be improved?
No sound did she made as she crept upstairs
No, it's not quite correct. It should be "No sound did she make..." - not "made".
When you invert, you have to add do-support. So your original sentence
She made no sound as she crept upstairs
becomes (prior to inversion)
She did make no sound as she crept upstairs
(The verb following the auxiliary "do"/"did" is untensed - "make", a bare infinitive - not "made".)
When inverted, that makes:
No sound did she make as she crept upstairs