"*Here is the way to fix the problem when your Ps Vita buttons wont work in games.*
First the reason this happens stems back to a rare flaw in the psp go. The L or R buttons will either take water damage, physical damage, or even heat damage for playing it too long and the glue that is under the L or R buttons will spred to the electrical and will cause the system to think it's being held in or broken. In the PS Vita case it will suspend the buttons from working in game...
The fix to this is one of two things depending on the underling cause.
1. Take apart your vita and remove the L and R buttons and you will see the white rubber components unplug them from board and clean the bottem where the glue was and connecting ends with Alcohol and cue tips. Plug them back in and all should be perfect.
2. If the above doesn't work just leave L and R buttons unplugged (this means the white rubber components as well) and restart your vita. All should work and you only need to buy new L and R components.
I cleaned the white rubber component with acetone, and it works fine now! It's not a big deal to open it, I would just advise people to watch a video first (some screws are well hidden).
Have you tried going though the safe mode options on the Vita (press power while holding the PS Button and the right shoulder button). Go through each of the options to see if this helps at all.