Default [Q] os problem

i have rooted my device lava iris 455 it rooted successfully,but when im going to use a new custom as prescribed by the xda developers..it will not processing,,well in fact when im trying to get to close my device root access,,the MT65XX preloader is not coming to my pc at any how,now when im going to boot my device it just showing the boot logo..and the total system has stoped in boot logo...my phone isn't working plz help me anyone?