I want to edit passwd

First he does it. But i closed en restart it.

en i want to edit but know he cant found vi :S

 vi /etc/passwd
vi: not found

It seems that vi is launched since vi says "not found".
I have no idea which file is this, but if the /etc/passwd not exists the vi should start without any error with a new file. 
I tried a lot of scenarios to get this error on my Wrt system by playing with directory and file permissions, but without success.

I would say to post the output of
ls -l /
and
ls -l /etc
but not seems to be a permission issue.

Which version of OpenWrt you are using?