Your question indicates some confusion about what a transformer does. A
transformer is two wire coils on an iron core. The different number of
windings on the input and output sides determine how much the
transformer changes the voltage. You cannot "reset" a transformer to its
factory settings.
Since the ZW is no longer working, there is most likely a broken wire
somewhere inside it. I do _not_ advise opening the box and trying to fix
this. If the broken wire is visible when the box is opened, it can be
fixed, but I urge you not to try that yourself. Get a technician to do
it. If the broken wire is invisible, it's somewhere inside one of the
windings, and that means the transformer must be replaced.
HTH
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