The broken stud can be pounded out, then a new one is pulled in. Use a stack of washers with a center hole large enough so the new stud doesn't get stuck in them. You'll need a lug nut without a center cap. Install it backwards with the flat side against the washers, then tighten it to pull the new stud in.
After installing the wheel, drive the car a few miles, then tighten the nuts again. ALWAYS use a click-type torque wrench when tightening lug nuts. The auto parts store will have a listing of how tight to make them. For most cars that value will be somewhere between 80 and 120 foot pounds. Cast wheels will have lower values; steel wheels will be on the higher end.