Hi,
I need to make attachments mandatory for each item of k2.

How can I do?

Thanks !!!

The easiest way would be via a simple K2 plugin which load a js script.
That script would disable the submit button until an attachment has been loaded.

Hi Krikor,
thank you for your quick response.

This plugin exists? I tried but I can not find it.

Thanks!

I do not think so. I can however direct you to an example plugin, getk2.org/extend/extensions/90-example-k2-plugin-for-developers which will allow you to develop your own without much hassle.