Hi Ruchi,
For this you need to change jsp page of language portlet.
You need to create hook for same of page.jsp.
<aui:form action="<%= formAction %>" method="post" name="<%= formName %>">
<aui:select changesContext="<%= true %>" label="" name="<%= name %>" onChange='<%= "submitForm(document." + namespace + formName + ");" %>' title="language">
<%
for (int i = 0; i < locales.length; i++) {
%>
<aui:option cssClass="taglib-language-option" label="<%= locales.getDisplayName(locales) %>" lang="<%= LocaleUtil.toW3cLanguageId(locales) %>" selected="<%= (locale.getLanguage().equals(locales.getLanguage()) && locale.getCountry().equals(locales.getCountry())) %>" value="<%= LocaleUtil.toLanguageId(locales) %>" />
<%
}
%>
</aui:select>
</aui:form>
You will find this kind of code on page.jsp located on
\tomcat-6.0.29\webapps\ROOT\html\taglib\ui\language folder. (
On Line number 80 )
Note :Remember by doing change in this means you are change something which will reflect on whole portal

Thanks,
Sagar Vyas