It purely depends upon what he/she has done to me and how hard he/she is struggling now. If it is forgivable and if he/she is in a really bad situation, I might help him/her. On the other hand if that person has done something really bad to me, as in something I will remember my whole life, in that case I might not help him/her.
I would say that it would depend on several factors, the first being why and how she turned me down. If she turned me down because she was with someone else and was straightforward about the reasons then I would not hold it against her. If she was cruel or deceitful in rejecting me then I would be less likely to help.
Also, the circumstances in my life would play a part in my decision. If she turned me down because I did not have enough money, but was now in a better financial situation then I would take that into consideration. If I felt she was only interested now because I had some money then I would not likely offer much help.
Yes right it depends on several factor. He turned me down because I can not give the things he wanted before but he asked for help right now because he knows that I will not turn him down like he did to me before..