First you need to post your computer information according to AMD Forums Rule: INFORMATION REQUIRED WHEN POSTING A QUESTION .
If you have Windows 10 installed, If you start and reboot the computer three times before it boots into Windows, by the third time, A Windows 10 Repair Menu will show up. Use that Menu under Troubleshooting to either Restore your computer before you updated the Driver or uninstall the AMD Driver that is causing the black screen.
Also you need to post the EXACT MAKE & MODEL of Laptop you have including Windows OS installed.
Plus post how your external Monitor is connected?