How can I reset iPhone camera roll to IMG_0001.jpg?
At the risk of you having done the steps, here is how it worked in the past using PhoneView:


Power off the phone.
Connect to USB and let it start (this way the camera app and others are not accessing the camera roll).
Launch PhoneView and in the settings turn on Show Entire Disk (Advanced Disk Mode)
Delete all pictures, files, folders from inside DCIM _(such as .MISC and 100APPLE, 101APPLE, etc... leaving just the DCIM folder empty).
Edit the PhotoData > MISC > DCIM_APPLE.plist file to set things to 0000 and 100 as desired in the xml file.
Disconnect the USB and power down the phone, never once tapping on any apps while you shuffled things under the OS and the Camera app.
Power on the phone and take a picture.



    DCIMLastDirectoryNumber
    100
    DCIMLastFileNumber
    251