I have a pug who suddenly went blind over 4 years ago. Yes, of course we still go on walks. You have to hold the leash close to your body, so she doesn’t get too far ahead of you and that you have control to guide her away from obstacles. Even though my dog cannot see, she enjoys getting outside and sniffing around.
I would encourage you to take your dog to the vet immediately about the toilet question. It is NOT normal for a dog not to pee or poop for days.
I do hope that he or she does not have some other kind of medical problem.
It does take time for a dog (and you) to adjust to the blindness, but I assure you your dog will adapt to blindness and still be able to enjoy many things as he did before the darkness set in.