In order to give you specific answers, we'd need to know what steps you followed and what procedures you took in your quest to run Windows.
It looks like the following page will show you how to restore your computer no matter what you've done to it: [link|https://www.howtogeek.com/190645/how-to-factory-reset-a-chromebook-even-if-it-wont-boot/|How to Factory Reset a Chromebook (Even if It Won’t Boot)|new_window=true]
In your case, however, you might need something a little more heavy-duty after having tried to install Windows. I think this page may have the answers you need: [link|https://www.howtogeek.com/279308/how-to-restore-your-chromebooks-original-bios-and-software/|How to Restore Your Chromebook’s Original BIOS and Software If You’ve Erased It|new_window=true]
Hope this helps.