I had a home equity loan a couple of years ago, at closing I discovered my name on the contract was David M. It should have been David W. I brought it to the attention of the loan officer. He looked at it and said, you are going to be David M. today, I don't want to change all the papers. Is this a valid contract? Thank you.

Yes, it's a valid contract. That is a minor mistake and a court will not invalidate the loan based on that. Also it is highly likely that one of the documents you signed at the closing was an agreement that you would completely cooperate with the lender if there were any mistakes in the documents that needed to be corrected.