My Android sytem is gone I have big problem here.
I wipe system partition on my phone, I know that I shouldn't have.
Now my phone without Android OS, I've try to flash it using custom ROM but it doesn't work.
Any idea how to flash it back to stock?
It always show error when i tried to use custom recovery from PC (using command prompt)
What stock ROM I should've flash it? Back to Android Lollipop or lower?
Thanks
Well, head on over to XDA-Developers and look for your phone.  If they have it there in the developer forums, you will probably be able to solve your problem with some research.

To get useful answers, you need to supply more information about your device.  What model is it?  Nexus 5,6, Pixel?  One of the Samsung or Lenovo phones?  HTC?  What version/patch level is on your phone?  Is the bootloader unlocked?  Do you have a custom recovery?

Armed with this information, coupled with an active XDA developer forum, and you should be okay.  There will be at least one post of the stock firmware for your device of one or more versions.  If you have the exact same on your phone, you can flash the system and you're set, though I'd consider doing it all after you backup your data.
{edit:  I just saw the "lenovo" tag on the post, so you're likely on a Moto X, G, or Z.  You will find a robust developers' forum over on XDA. }