In entering my Coop information from 1098, there is a question: total on loan as of 1/12019. this is not provided and it's not the loan from the bank. where do I find it

You will need to find out what your portion of the mortgage loan is in order to claim the interest. If the Coop provides the amount of interest they are allocating, they should be able to do the same for the loan amount. 

This is a new requirement (for claiming the interest) in part because of changes related to the Tax Cuts and Jobs Act.