Chosen Solution
I replaced the Trackpad with one from ifixit. The cursor is responsive however clicking doesn’t work, the Dock doesn’t respond or appear at all and I cannot open any menus . I checked everything and even repeated the process and made sure the connections were secure. I replaced the new with old and functionality returned other than drag and drop which is what prompted the upgrade in the first place. Cheers
To help isolate the issue, try using an external USB mouse. Make sure your battery isn’t swollen. There is also an adjustment screw on the trackpad. See step #9 at the very bottom of the photo on this guide: MacBook Unibody Model A1342 Trackpad Replacement UPDATE If you are getting the same symptoms with an external mouse, it’s a very good bet the problem in not with the trackpad. My guess would be a virus. Start up in Safe Mode by holding down the Shift key and tell us if the problem persists,
Here’s a picture of the adjustment screw
