Lightroom hard drive failure

I have been using Lightroom Classic for quite some time.  I went to back up the catalogue and the hard drive failed.  I have backed up most of the photos on another cloned hard drive, but I don't know how to access them.  Lightroom keeps opening up a previous catalogue, which makes sense.  I would like to get the newer photos into the catalogue and back it up.  Is this possible?  If so, how do I do this?