Uploading files according to creation/modification date

When I upload files from my computer to my website I need the facility to just upload any file which has been created or modified after a certain date. I can do this for files in a single folder by just arranging them accoring to creation/modification date and then just selecting the top ones which fit the criteria. The problem occurs when there are also files in subfolders - I have to go into each subfolder and repeat the process - I need either a "macro" to do this or else the abilty to see all the files in a folder, including files in subfolders, at the same time, in order to list them according to date and then just send those that meet the criteria

Thanks