I'm guessing that you have an easy fix. With the bolt all the way closed, raise the muzzle to near vertical and then pull the trigger. (Hopefully the rifle isn't loaded!) Firing pin will likely fall out. If not, shake the rifle a bit. If that doesn't work, try wading though this long thread or post a clear photo looking into the rear of the bolt. Or both!
Click on link below:
Type 99 Bolt Assembly
ETA: For the firing pin to fall out, it must be oriented properly. Make sure the sear lug is at the bottom!