Last week, I wrote my professor a email and asked her whether she would like to write a recommendation for me. She seems quite positive and asked when would be the submit time. I replied promote about the deadline would be in two weeks. Since then she didn't reply any more. I asked early this week whether she need extended time to write the reference letter. She still didn't reply. The deadline will be next week. So does the submit time didn't work for her? how can I do now?
Two weeks is very tight; how many letters did you ask her to write? Was it for multiple schools / grants?
A month's notice, at the minimum, is typical for multiple letters - she seems unwilling / unable to meet those deadlines. But, try again, and good luck.