Is the car in the air? If so drop it and put weight on the tie rod.

 

If you have a helper and along prybar ,
pry the tierod into the knuckle,
then fit the nut.

 

 

Engage as much thread as possible with the nut. They normally go on easily, so if the nut is hanging and spinning the stud it's possible that the nut is not correct (use the ones that came with the new tie rod) or is damaged. Ditto the end of the stud -- it it's been hammered at some point, the end may mushroom enough to keep the nut from fitting. As a last resort, you can use a narrow "pickle fork", the one sometimes used to remove a tie rod, and use the wedge to pull the stud tight into the tapered hole in the arm. Then tighten the nut. As another last resort, use a welding-clamp split Vise-Grips around the nut to hold the tie rod end to the arm tightly.

 

hold it together with some channel locks for a bit..just needs enough to grab