If the active layer has no pixels in the selected area (transparent), you'll get that error.
Also, have you tried a brightness/contrast adjustment layer to see if that works?
You might not have a layer selected.
Try flattening a copy of the image and see if you get the same error.
If not, make sure you have a layer selected.
You may want to try MACnTUTOR's very excellent suggestion of trying an adjustment layer.
I normally use an adjustment layer for Brightness Contrast, but there is no visible modification. That was what promped me to use image/adjust which produced the error.
There is only one layer and it is active.
I have tried on about a dozen other images and get the same error on each.
Can you show a screenshot with the layers panel visible and the image window immediately before making the image adjustment?
You might also want to try a preference reset in the meantime. Go to Preferences >General > Reset Preferences on Quit. You will need to restart Photoshop after clicking OK.
I have uninstalled and reinstalled PS and the problem has been cleared up. Everything else I use on a regular basis was working fine, but obviously there was some small glitch in the installation. Thanks you all for he responses
Glad you're sorted