Under "Site Diagnostics" in my adsense account; I am getting many warnings like Google crawler blocked the url URL-NAME for the reason of "Robots.txt File" I know those unfound pages are not good and need to be fixed; but is this has any impact on my adsense account? (e.g. getting banned for this?).
I don't believe you will get banned for sloppy house keeping, at least I have never heard of this happening, but you may want to get them cleared up just to keep on top of things. You also never know what small part these may play for your SERPs. And now days every little bit helps.
No I dont think you will get banned for this but Its good practice to have a clean site. I check this from time to time along with my error logs.