Is it just the brightness slider missing or is it the complete basic panel in Develop module?
If its the complete basic panel which includes brightness slider, go to Window menu > Panels > check Basic.
Its just the slider- Basic is checked everything else is there.
If you are using the new develop Process Version (which is called Process Version 2012), you will not find the brightness slider and several others, these sliders have been replaced by new and superior tools in the Basic panel.
By default, Lightroom 5 will process newly imported photos using Process Version 2012, and so you will not have the brightness slider. Photos processed in earlier Process Versions will remain in the older Process Versions (unless you specifically change it), and so you will see the brightness slider.
I don't understand- I have been using it for about yr and a half now. It just disappeared.
I really just want it back. what do I need to change to make this revert?
Perhaps you have accidentally changed a setting somewhere, or changed an import preset?
In any event, in Lightroom 5, you do not want to use the old process version with the Brightness slider for newly imported photos, as there are now superior tools available, resulting in much higher edited image quality than anything you could get with Brightness. These take a little learning, but the end result is worth it.
There are many tutorials and examples to show the differences, here is one: Where Are My Lightroom 4 or 5 Develop Controls and What's That Lightning Bolt Below the Histogram? | Laura Shoe's Lightr…
Thank you DJ. Having the link is really helpful.