A family of Microsoft word processing software products for creating web, email, and print documents.
It is not necessarily the wrong file for your active Contacts folder. The Contacts folder can be stored in either an OST or a PST file. If you are using an Exchange account, your Contacts folder is likely stored in the OST file.
If you are using a POP3 or IMAP account, your Contacts folder is likely stored in the PST file. You can try to verify which data file your Contacts folder is stored in by checking the location of the Contacts folder in Outlook.
To do this, right-click on the Contacts folder in Outlook, select Properties, and then select the Advanced tab. The location of the data file should be displayed there.