I accidentally deleted system off of my Android device, how can I get it back?

[AC Question]

I accidentally deleted "system" off of my Android device

Here's what happened. I had basically rooted my Android device, in hopes to get rid of the Adware and such that was on it. Everything was going fine until I accidentally hit delete on the "system" application. I rebooted the phone after noticing I could not even see the home screen. Now it is stuck on the boot screen. What can I do from here? Is there some way to install "system" back to it from my computer? Even when I plug it into my computer while it's on the boot screen, I cannot access any folders.