find pdc emulator.  from a command prompt, run:

netdom query fsmo

run this on the pdc emulator in powershell as admin to find lockout events and identify which computer caused the lockout:

get-winevent -filterhashtable @{logname='security'; id=4740} | Where-Object -Property Message -Match 'username' | fl

Run this to verify if user account is currently locked out:  (requires AD modules in powershell)

Get-ADUser -Identity 'username' -Properties LockedOut | Select-Object Name,Lockedout

Run this to unlock the account from powershell:

Unlock-ADAccount -Identity 'username'