MacBook Air 13" 2014 Turned off randomly, won't turn back on
I don't think there's much you can do except for contacting Apple Support. You can test if the issue is with your display by using Target Disk Mode and booting up off of your Mac. This allows your Mac to act as a hard disk. To boot in Target Disk Mode, press T on your Mac when it is turned off. Then, you will need another Mac. Use a ThunderBolt cable to connect the Macs, restart the second Mac (the working one), and press Option while it starts up. If you see your Mac that doesn't work in the Boot Menu of your Mac that does work, then your computer still partially works and you can recover your data. If it doesn't then again, your best option is to replace the Mac or contact Apple Support.