Hello,
I recently rook over at IT director at a K12 school. I have disabled the previous IT directors AD account and found my Veeam backups didn't run. I was also unable to launch Vsphere. Upon investigation of this issue I found VMware VirtualCenter Managment Webservices service & VMware VirtualCenter Server service had AD Credentials associated with the startup process, I changed them from the old IT director to my AD creds and now cannot start either service. See attached screen shots, if anyone has something to try that would be great!