1) http://SERVER/Reports
2) Show Details
3) Check if DataSources exist and create:

Data Warehouse Main
Connection String: data source=SERVER;initial catalog=OperationsManagerDW;Integrated Security=SSPI
Credentials stored securely in the report server: domain\username and pass

WSUS Database
Connection String: data source=SERVER;initial catalog=SUSDB;Integrated Security=SSPI
Credentials stored securely in the report server: domain\username and pass

SCDW
Connection String: data source=SERVER;initial catalog=SystemCenterReporting
Credentials stored securely in the report server: domain\username and pass

Data will regenerate itself