If you're adjusting the view via "Studio", you should find the field in "existing attributes" UNLESS it is already somewhere else on the UI. Fields that are already present on the UI are not listed in "existing attributes".

It might simply be currently invisible. Go to the "View" tab in Studio and activate the check box "show invisible elements". Once it is visible again, you can check and modify the invisibility condition to bring it back into view.

If you don't see it immediately, it might have been moved into another register tab or some other part of the form, so look at those as well.

If you really think you deleted the contact type, you can verify that by going to Settings-->Technical-->Models, selecting the model res.partner and check if the field company_type (person, company)) and type (contact, delivery, invoice, other) are still in the model. It would be pretty surprising if you had actually managed to delete them, however.