bold fonts also needs to be embed. Bold fonts are a different set.

 //to embed using css file
@font-face {
    src: local("Verdana");
    fontFamily: ArialEmbedded;
    fontWeight: bold;
}
// to embed bold fonts in actionscript
[Embed(source='../assets/Verdanafont.ttf',   
       fontName='myVerdanaFont',  
       fontWeight="bold", 
       mimeType='application/x-font'  
    )] 

check this link, to embed bod fonts in flash
http://heidibrebels.be/blog/archives/2006/flash-embed-font-bold

Thanks for ur replies.But i didnt find any solution.My code like this

var request:URLRequest = new URLRequest(languagecode);
var ldrContext:LoaderContext = new LoaderContext(false, ApplicationDomain.currentDomain,__secDom);
ldrContext.applicationDomain = ApplicationDomain.currentDomain;
var ldr:Loader = new Loader();
ldr.contentLoaderInfo.addEventListener(Event.COMPLETE, onloadcomplete);
ldr.contentLoaderInfo.addEventListener(IOErrorEvent.IO_ERROR,handleioerror);
ldr.load(request, ldrContext);


private function onloadcomplete(event:Event):void{
var appcls:Class = (event.target as LoaderInfo).applicationDomain.getDefinition(txt1.text) as Class;
Font.registerFont(appcls);
var obj:Object = new appcls();
textArea.setStyle("fontFamily", obj.fontName);

}


Here textarea text had some bold text.I need to embed font with boldness in flex without
modifying flash code.
Can we embed regular font of flash to bold text in flex.Can u please tell the solution

you cannot make an embedded font bold unless you have embedded it. You must embed the bold fonts along with the regular one else either the text won,t show up or the fonts wont appear bold. You can use either of the methods mentioned by Redbull , using css file or using actionscript