You have Ubuntu, and you're sad? Dude, you're better off. Trust me. Now, when you say to t you don't have files, do you mean that TWRP shows 0mb for memory space, or that your internal memory is empty? Either way, I suggest flashing the stock image, if all else fails.
But for now, you could always try adb push to get the file onto the tablet.
And for the record, I only use Ubuntu for flashing nowadays. All you need to know are the right commands to use. Toolkits are an easy solution, but they leave you stranded when something goes wrong....just like now. Besides, you only need to use the commands listed in the Windows guides, and disregard the process of setting up everything for the PC to recognize the device. Linux recognizes Android by default since Android was built from it.
Let me fully explain my two options that I have given you.
Option 1) ADB push
Locate the file that you want to push to the tablet, and copy it to the '/home' directory. You can always navigate to the file using the 'cd' command, but it's much easier to move the file. In recovery, make sure that the SD is mounted. In Ubuntu, use:
adb push RomName.zip /sdcard/RomName.img
Then use the tablet to locate the file and flash it.
If that doesn't work, then you might need:
Option 2) Flash Stock img
Download the img for razor. Boot into the bootloader (power + vol down). Then put it in your '/home' directory, and use:
fastboot erase system
fastboot erase userdata
fastboot flash system system.img
fastboot reboot --> When completed
I don't think that it is necessary to wipe before you flash the stock img, but it doesn't hurt to do it. So remember that the stock img will wipe everything, and perform a factory reset. The only thing that it will not do is relock your bootloader, I didn't think. Simply reroot your device
fastboot on unlock --> if necessary
fastboot flash recovery RecoveryName.zip
The flash SuperSU in recovery, or flash the rom of your choice (you will have to use adb push again).
I hope that this helps, and if any of my information is erroneous, please let me know. I'm not a pro at this, but I do know how to get myself out of sticky situations.
Phone: HTC EVO 4G LTE
Sense 5, S-Off
Tablet: ASUS Nexus 7.2
Rooted, Custom Rom & Kernel