Process of elimination:

- Try a different hub, or better yet, plug directly into your PC
- Hold the button on the front of the PICKit 3 when you power it up until the lights blink. This forces a RESET. You may have to program it with MPLABX IPE at least once to get a fresh PICKit3 firmware reload.
- Try programming a different PIC to see if it's the chip and not the Programmer