First, the spell, later, a warning.
To get a lover back quickly you may use any type of poppet spell. A good one here on this site is the 'Poppet Binding Spell', I am new here and haven't been able to review/practice all the spells posted here, however, I have done a variation of this spell many and it works, provided that you have enough focus and strenght of will. I would add to the poppet any type of human residue, like her hair and fingernails (nail clippings), if you have them, to enhance the power and expite results. Work with the appropiate moon phase, planetary hour and day of the week for optimum results.
Now, the warning.
Love, passion, binding spells are all extremely dangerous. Do not play with other person's will. If she does not want to be with you anymore then practice a healing spell on yourself and move on. Binding spells can backfire specially if the person just broke up with you and you are very, very vulnerable. In this state your focus is not good. Do not coerce the other person to love you, if you succeed the person not only will return to you but will also desire, stalk you and never leave you alone. It will become an unnatural relationship between you too. She will not be herself around you and you will feel bad for doing this to her. And this can go on for years unless you un-bind her from you.
Examine your intentions before moving forward with the spell.
And remember to use a healing spell on yourself.