Hi Deeplakshya,
How were you feeling on test-day? Verbal is the very last thing that you had to do on the test; this is speculation, but if I had to guess what happened just from looking at your scores, I'd say you were overtired and overstressed and just couldn't maintain focus for the last hour.
Does that sound accurate? I hope so, because if it does that's a good sign--such difficulties are easier to address than a fundamental revision of your testing strategies. Make sure that you're taking full-length test, including the essay, to build endurance, make sure to rest and taper off studying in the week leading up to the real test, and try some common stress-relief exercises such as stretching or deep breathing.
I'm guessing a little here, but I hope I'm on the right track. If not, though, let me know if you have any other questions!