how do i make these vertex lines straigt? because when i move them the form is stil the same
You can try to move them along the edge, with G+G, or to smooth them with the Ctrl+V>Smooth vertex.
it doesnt solve it
try to use loop tool !
A dent like this with Subsurf usually indicates some kind of mesh problem. Make sure you don’t have double vertices there.
your title should be “How do I straighten edges ?”
I don’t know why you call it flat vertex.
Anyway, you seem to have some angles without vertices which to me is a complete mystery.
I would try to go in mesh > vertices > slide, or delete the vertices and fill the face again. Maybe use the knife to recreate the edges.