The 5505 is gone end of life and end of support. You wont be able to get a software from cisco software website. the last release on the cisco 5505 is 9.0.1 to 9.1.7.
i doubt you can get the software from cisco unless you search on internet if you get a copy from any where. but i wont recommand this way as we dont no if that copy could be temper. get in touch with your gold partner account manger or cisco account manger might they can help you on this.
please do not forget to rate.