Question

My presonus studiolive III change mic input through NSB or AVB   network box from pre amp to digi gain

and after that I could not get any sound  from the speakers .

Answer 1

It looks like you should consult the manual and check the first basic steps of connecting mixer and stagebox. This is section 2 of the "NSB-Series_Stageboxes_Owners_Manual_EN_V3_25032019", which you can find in the download area of your mixer. For the SL 32 the link is https://www.presonus.com/products/StudioLive-32/downloads. Section 3.1 "Remote Preamp Control (Console Mixers)" might be of special interest for your question.