I am using the default k2 item. php in my website desktop version, i prepared a new item.php which is suitable for mobile layout. can i know how i can redirect the layout if it is mobile to the mobile template?

Is there a way you already target your mobile site?
Do you use http request, for example?

it is the same website, but it has a mobile version ready, but the item.php which i am using is not suitable for the mobile layout, i am using 3 columns and some changes in ti. i prepared an new item.php for mobile version and i want to redirect to it if it is mobile.

In order to call a completely different file for your mobile version you will have to use an extension that gives you the ability to load a completely different joomla template based on the device, mobile/tablet, etc. There are many if you check the JED.

The option I will recommend however is to just change the layout only through CSS manipulation and avoid the use of a different file. Add classes that will change according the media query they are in.

the problem is i have two columns in item.php k2 item view (Left and right column) and i try to make them one column in mobile.css without any changes.!

Did you ask your template provider/developer to help you with this?

yes but i made those changes to the template, (the 2 columns), their default template is one column,

it is an example for the item.php layout i am using.

www.elmarada.org/our-news/marada-cadres/27156

you can see the right and left column which i need to make them 1 column in mobile layout

Instead of having the styles put right inside the item.php you can just put 2 classes. One for the left container and one for the right that will contain those exact styles you already have.

Then when you are on a mobile device you will give a 100% width on both of those classes and you will have 1 column.