If you are switching using Duo Mobile on one phone to another and you still have the old phone or another previously enrolled device, you can reactivate Duo Mobile on your own.
But if you don't have your original phone or another previously enrolled device available, request help from DoTS here. However, if you need to use Duo multifactor authentication to access to UWRF technology soon, it is best to call or visit the DoTS Service Center to get immediate attention.