A: When you delete a contact it is moved to your Archived Contacts area which can be accessed via Contacts > Archived Contacts.
If you ever need to restore an archived contact back to your "live" list just tick the box on the left of the ID number then click the button at the bottom "Restore Selected".
Hint: Email address is a unique identifier so if you are trying to create a new contact record with the same email address as an archived contact then there are 2 options open to you:
1) Edit and disable the archived contact's email address and re-save. Then you can create a new contact with the original email.
2) Restore the archived contact and then use that record to build with for the future.