I picture would help ,if the bolt is sticking out you maybe can heat the nut part and then cool it really fast with water. Then you can grasp the part of the broken bolt with a set of good vise grips pliers and remove the bolt take your time screwing it in and out (penetrating oil helps) if it's broken off flush you need to grind the bolt flush with the surface and center punch the bolt then drill the center of bolt take your time drilling go slow let the drill bit cut you should use cutting oil to lube and cool the drill bit,if you go to fast you will burn up the drill bit and it will take longer to drill (bit gets dull) and you could also break the bit in the hole remember it's a lot harder to remove a hardened steal drill bit., once you have drilled through the bolt you move up in drill bit size to around half the bolt diameter and then you use a easy out bolt extractor.don't forget to apply penetrating oil and let it soak,if the bolt is still frozen in you could try heating around the bolt and then cooling it fast with water ,if this doesn't work you maybe will have to drill to almost as large as the bolt diameter and use a tap to remove the damaged threads as long as you are centered in the hole,last resort is to drill out bolt and install helicoil(repair thread kit) you will have to buy the kit at a auto supply shop or machine shop. Good luck on the repair!
2012 silverado ext cab 4x4 ,5.3 L , 6 speed trans,3:42 final drive,tow package standard box 6 1/2 foot . 2014 honda forza 300 scooter, #2 2015 honda crf 250 L (Dual sport)