Searching for a file, with name Last Sunday through Saturday

Hi List,

I need write a script that looks for a file with name File_03-09_to_03-15_data.txt (File_LastSunday_to_LastSaturday_data.txt). If this file is not exists i have to look for a pervious weeks file like File_03-02_to_03-08_data.txt. This loop should continue untill it get a file or no file in the last 2 months.

Please share some logic. I am pretty new to shell scripting..

Thanks
RejiRaj