How do i get the speedometer apart on a 250cc v star 2009

Sounds like the sensor broke apart. I would be taking the side cover to see what bits are floating around!

https://www.google.com/search?q=2005+Yamaha+V-Star+1100+Silverado%2C+my+speedometer+stopped+working

this is the sensor

https://www.google.com/search?q=2005+Yamaha+V-Star+1100+Silverado%2C+speedometer+sensor

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Page 35 of your Owner's Manual

https://www.manualslib.com/manual/1192373/Qlink-Lg250.html?page=35#manual

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the speedometer worm gear not working located in front wheel.Replace it.

Check if the cable is not broken by twisting the inner cable anticlockwise and observe the speedo to see if it moves.
If ok, put it back on the wheel, making sure that the pin with flats is in the groove and tighten the nut. Good idea to pull the inner cable out and grease it with a light grease.
Good luck.
Also found some links.

http://meiguohosting.com/How-to-fix-a-malfunction-speedometer-for-your-2009-Yamaha-V-Star-950/
http://yamahaclub.com/forums/topic/19481-v-star-speedometer/

Take it to a dealer and have them reset the bike. They can plug intot he bike and reset error codes that will prevent the bike from running.

http://www.bikebandit.com/houseofmotorcycles/2009-yamaha-v-star-classic-1100-dark-bluish-gray-metallic-8-xvs11awyg-fuel-tank/o/m144560sch596818

From the above exploded view, it would appear that you need to remove the rear screw (#35) and the housing should come off.

may hav a bad connection--failing module-or computer issues--get it scanned-------get a clymer manual for bike repair