Hello @PeterT
If you are using azure lab services, please go through this documentation
https://learn.microsoft.com/en-us/azure/lab-services/troubleshoot-lab-creation
https://learn.microsoft.com/en-us/azure/lab-services/retirement-guide
If this is about Azure dev test labs, please look at the troubleshooting document link https://learn.microsoft.com/en-us/azure/devtest-labs/troubleshoot-vm-environment-creation-failures
If you are still facing the issue, please share more details on the exact issue you have with screenshots or error message in a comment and tag me.