attempt to read or write outside of disk 'hd0'

[Don]

I've been running 14.04, but my hard disk died. That's not a catastrophe; all the important data I have are backed up to at least four other drives. So I bought a new hard drive and attempted to install the new 16.04. The installation seemed to go well, but when I try to boot to the new drive (having removed the dead one), I get the message above, and I don't know what to do about it. I get "entering rescue mode," but I don't know how to designate the new drive as hd0.
I shall be grateful for any ideas.