Unable to factory reset gt-s5830i I'm in a big trouble let me explain.
I have a GT-s5830i where I installed MIUI, I have also CWM Recovery 5.0.2.8.

Now for many reasons I would like to factory reset my device to it's original ROM, what I did:


Enter recovery mode
Wipe cache
Wipe dalvik cache
Wipe data/factory reset


The system stuck here with this error message

Error Mounting /sdcard/.android_secure!
Skipping format...


Now I rebooted the device and for 1 hour is on boot Samsung logo, it do nothing, just stay on Samsung logo showing GT-s5830i

Please help me I don't want to buy another phone.
Thanks in advance
Sonia
Reading your question a second time, I just see you're on the complete wrong track (a thing we call the XY problem):


  Now for many reasons I would like to factory reset my device to it's original ROM


That's not possible at all. You overwrote this when flashing MIUI (for details, see our factory-reset tag-wiki). You'll have to get yourself a ROM file to flash (see: Where can I find stock or custom ROMs for my Android device?), and flash your device again if you want to "return to stock".

That said, it makes no sense to get your "supposed solution" to work – as even if we did, it would not solve your issue.