Hello velma274,
On your iPhone go to Settings > Scroll all the way down to Apps > Scroll down to Phone > Scroll down to Blocked Contacts and click.
There you will see a phone number list of all your blocked contacts.
You can in the top right of screen click on Edit. Then click on any of the minus signs to UNBLOCK the contact number.
If you want you can click on a blocked number and add it to an existing contact or creat a new contact with the number.
ALSO;
Open up the Phone app then click on Contacts. At the bottom of the contact info you will see BLOCK CALLER. Click on it and the number will be added to the Blocked Contact Lists