I recently checked my credit and i have over $11,000 of medical bills from 2014 that never got covered. With whom do i need to contact to try and get this covered and taken care of?

I was planning on getting a loan so i looked up my score and saw that medical bills had not been covered in 2014. I had no way or reason for checking before and never received any bills so i could of taken care of it then. How can i go about getting BCBS to cover bills that should of never reached a collectors office to begin with?