When you are not happy with you department how do you explain to your Employer to change your role?

You all have spoken well, my own point is that it's better to concentrate on your current role you are employed for and contribute to the role you are admiring positively then speak with your manager about change of role

Best way is to give your100% effort to the current job so as to prove your willingness to be worthy for your organization and team, then explain to your manager the unwillingness to continue with the current profile and if given a chance in a new profile you will give the same100% or more to complete the task.

I will discuss with my employer and find out a good solution for the matter.

I do not complain but find a way to make my own contribution positively.

i will explain to my employer properly with please 

When you are not happy with your department there might be two reasons:

a] Are the colleagues in ur department or environment makes you unhappy

b] Is the work you dont like to do in the department.

If the reason is a] you can talk with the heads and HR if you facing an issue that will improve the circumstances you never know same stuff might be with others. Express yourself and be open as you spend half of your time in office.

If the reason is b] You can talk with your head / employer as you are not happy with the task/work assigned to you and looking forward for better and interesting opportunities at work place.

When you express the doors open up.

But are you sure if the work or department if change you will be happy.

Note:

If you do the things with full heartedly and interest and live with the work you will always be happy to work.

The happiness always lay within.

Experts herein already gave the right way of approaching, while concentrating and giving your100% on the current role you are employed for and put up the request before the concerned authority for the change will do. As any responsible authority will definitely look into the genuine request and will help to pursue the matter in a given time where your services in current role can be replaced or till make an alternate arrangement. Thanks.

i will tell my employer that i am interested to work in other department.

Use some win win negotiation skills, be honest and clear.                    Thank you.

The happiness in job different from capability to perform it efficiently, in case of reasonable cause of being unhappy, I shall declare to the employer the reason of my feelings towards peers or environment away of capability of succeeding within this stress.

This is a very common scenario, first of all talking to the employer about this brings you a negative remark, since the impression would be that you are not a team player. Try to sort things out talking to your coworkers in your department and should that fail, then go to the employer to share your inconveniences. Sometimes things can go bit personal, try to play it out official. Good luck.