Partitions wiped

Hi, i need help. I have rooted my tablet with TWRP to use a custom rom like many of you guys and it seems like all the partitions have been wiped.
When i try a stock rom installation, it says E: can't mount data or system and then my tablet freeze. It there someone who have a backup of the partitions for a nexus 7 16gb? Or someone who has had this issue before and willing to help?

Thank you in advance

Partitions backup

Hi Guys,
Another new owner of Mi Note pro here.
Anyone found the way how to backup IMEI and all partitions data (nv data) to easily recover phone after losing it? Been trying to find some tutorial however it seems as none is working for me.
Any idea?

Is there any tested method to mount Ext4 or NTFS partitions on Android 64 bits v5.1?

After long days trying to implement some filesystem that allows more than 4GB file size on my Jiayu S3 with a Xtreme ROM (not ROM stock, but still Jiayu official MOD) based on Android v5.1 64 bits, I have concluded that maybe, as for today (September 2015) there is no way to achieve this.

So, please, could someone successful on mounting NTFS or EXT4 (preferred) with a 64 bits Android version tell me how he did it?

I tried multiple tutorials (some from XDA) and apps, but they all fail.

Unable to mount partitions after flashing TWRP on Nexus 7 (2013, WiFi, flo)

I just bought this device a week and I haven't even rooted I wanted to install Cyanogenmode and follow through the instructions and flashed TWRP through fastboot commands from Windows7 using Minimal ADB and Fastboot [8-28-15].
I got the TWRP recovery but I am not sure what have I done wrong, when I am in the TWRP recovery, it does not show any partitions so I am unable to install any ROM on it.

I have also tried to use this thread: http://forum.xda-developers.com/nexu...overy-t3064562 when I flash the given recovery from fastboot commands from this thread, the recovery get stuck with bootloop. So then I restored it back to the original TWRP 2.8.7.0.

So at this point now I can only access bootloader and the recovery which does not show partitions.
At this point Is it possible for me to go back to the stock ROM somehow? Please advice. Otherwise I might be able to return it because I have only bought it few days ago.

Regarding Dual Partitions

Have these two partitions (System1 and system2) been there since Mi3 was first released or was it introduced later via an update by Xiaomi?