The adjustment brush in my CS5 Bridge is no longer working
This is a tool in Adobe Camera Raw (ACR) and ACR is a plug in that works in both Photoshop and Bridge. If you choose to open a file by pointing at it in the Bridge content panel it opens in ACR using Photoshop.
If you choose to Open In Camera Raw it opens in ACR using Bridge.
So first test both options, but it is likely you will get a better answer in the dedicated Camera Raw forum.