move a wordpress site from one domain to another

I recently lost a domain that I had registered by not renewing it early enough. I am trying to copy the files to a new domain but have no idea what to do.

I have checked the support files and most of them use the backend of wordpress to export the site. I cant access the backend so I need to transfer the files and reconfigure the database files to the new domain.

Please can someone assist or point me i the right direction

Thank you in advance