Site URL problem

I recently changed my sites homepage from .com/members to .com/members/welcome as I thought it would fix a redirect issue but it has now given my entire site a 404 and I can’t even access the wp-admin

My original site was at a .com/members/wp-admin but now I can’t access that even.

Does anyone know how I could fix this issue? I have a bunch of students starting tomorrow and now I can’t even access my site at all.