How can i fix my 2005 Honda Rancher?

I don't know anything about your machine, but on most bikes the device that sends the gear signal to the dash is a rotary type switch with a number of contacts. The switch is located on the end of the shifting drum, the shaft you rotate when you shift gears. I'd be checking the switch to see if it's loose, damaged or binding and in the process, keeping the shifting drum from turning. It will be located behind the cover that's behind the gear shift lever. The shaft the shifter turns will have a piece that's almost in the shape of the letter "F", with the two short bars having springs and hooks that catch on the shifting drum. Check to make sure the springs aren't broken or the fingers bent or worn.