one thing to note though, factory reset will only reset system files/folders. so if for example you have another folder in your internal SD na hindi part ng system, it will not be touched by factory reset so it will still be there (the app related to it will be gone though, will need to be reinstalled). example nito is something like titanium backup app. it will create a folder in your SD card and even if you factory reset, the backup files will still be there but you will need to resintall titanium backup to be able to access those files.