I am a left handed man, i do istanja with right hand because it is very difficult to do it with left one.is it right or not. Please give me suggestion in the light of hadis .
The correct way is to use your left hand to do Istinja', and one should struggle to use the left hand and should get ones left hand used to it. And if one can't actually use his left hand for some reason, then you can use your right.
لا يكلف الله نفساً إلا وسعها لها ما كسبت وعليها ما اكتسبت ربنا لا تؤاخذنا إن نسينا أو أخطأنا ربنا ولا تحمل علينا إصراً كما حملته على الذين من قبلنا ربنا ولا تحملنا ما لا طاقة لنا به
Allah does not charge a soul except [with that within] its capacity. It will have [the consequence of] what [good] it has gained, and it will bear [the consequence of] what [evil] it has earned. "Our Lord, do not impose blame upon us if we have forgotten or erred. Our Lord, and lay not upon us a burden like that which You laid upon those before us. Our Lord, and burden us not with that which we have no ability to bear.
Surat Al Baqarah Ayah 286
For more information see this (Arabic)