Screen Not Working and Lock Button Stuck
Method 1: Reboot iPhone by setting "Bold Text"


Open the Settings app and head to “General”
Go to “Accessibility” and locate “Bold Text”, flip that to the ON position
An alert will show up saying “Applying this setting with restart your iPhone” – so tap on “Continue” to immediately soft reboot device


Method 2: Restart the iPhone By Resetting Networking Settings


Head to Settings app and go to “General” and then to “Reset”
Locate “Reset Network Settings” and select it, then tap to confirm and reboot your phone.


If the issue is still not solved you'd better to call Apple or have someone check for you. Or you can check hcqs.cc for replacement parts and repair it yourself.