1. From Setup, enter Data Import Wizard in the Quick Find box, then select Data Import Wizard.
2. Click Launch Wizard.
3. Select Accounts and Contacts, then select Update existing records.
4. Set Match Contact by to Salesforce.comID.
5. Set Match Account by to Salesforce.comID.
6. Select Update existing Account information.
7. Select the CSV file that contains your import data, andclick Next.
8. Map the contact ID, phone, and address fields to the relevant columns in your CSV file.
9. Map the account ID and other fields to the relevant columns in your CSV file.
10. Click Next.
11. Review the import settings, and then click Start Import.