Adding Standard Fields when customizing layout

Adding Standard Fields when customizing layout

Hi 

I've been customizing the Contacts Layout and have renamed "Contacts" to "Tenants" as well.

I don't seem to be able to add in standard fields like "Salutation" to the form sections I've created as I can't find
the "Salutation" field. It is not on the "list of removed fields". I can't recall if I removed it originally from an original section.
There also appear to be a lot of standard fields missing from the "list of removed fields" when you compare between the list of fields available to what is on the list. 

Is there anyway to:

1. Reset the Contacts layout to the default setting
2. Or add the missing fields to the "list of removed fields" so we can add them back onto the form.

Thanks

Gene