Help! SD card and internal memory is disabled.

[AC Question]

Please tell me how to install any OS system in smartphone without SD card and without internal Storage, I have just device storage in my phone. I don't know how to fix that issue...On my smartphone because of some rooted issues and due to deleted some device files. my SD card and Internal Storage will be disabled. After lots of searches I done nothing. I don't know how to reinstall and OS system without both of them. How can I fix this problem. It is most serious for me.
My cell is MIUI 6.

Thanks in advance to support me....
waiting for your response.......