Thanks for the response.
I entered Time Machine, located the 'Lightroom' folder in 'Pictures' and restored the .lrcat & .lrdata files from there. When asked, I replaced the existing files on the hard drive with the ones on the Time Machine. I then opened Lightroom and imported the photos but the adjustments were missing.
When this did not work I replaced the whole 'Lightroom' folder from the Time Machine backup but I had the same result.