for the advice i'm giving, i'm assuming that there's a hole in your model at the spot you were trying to fix.

if you highlight all the stray verts and scale them all as close to each other as you can, you should be able to merge them together into one vert (if it won't do it, increase the tolerance value), and then from there you can once again merge verts with one of the vertices that make up the hole.

if that doesn't work, just delete the whole polygon, and using the append to polygon tool, recreate it (click on one edge of the hole, and then follow the arrows on the other edges that appear).