Is the kill switch on...? DAMHIK.
Taking it to a shop seems rather drastic. The speedo calibrator wouldn't affect anything that would keep the bike from running, but it's perfectly possible to accidentally unplug or otherwise booger up something else along the way.
Also, more information is needed than "won't start". Will it crank? What happens?
Which calibrator did you install, and how, and where? Is it plugged in to the right place?
What bike? I'm assuming a Vee of some sort.
2002 Suzuki DL1000 V-Strom, Dark Metallic Space Blue
1983 Suzuki GS850G, Cosmic Blue
2005 KLR685, Aztec Red - Turd II.2, the ReReTurdening