how do i replace the bottom hinge on my necht fridge?

You need a new hinge and it doesn't look likely that you will find one.

You probably found this page when you were searching for Necht manuals yourself, to see whether they detailed how to remove doors to change hinge handing etc. You probably missed the rather damning commentary further down the page:

https://www.ukwhitegoods.co.uk/help/about-the-appliance-industry/manufacturer-information/2776-necht-domestic-appliances

zcvadsv
May 2020