HELP!

If you want help, you should let folks know what you shoot.  If it's an A5 or a 98, just take the two halves of the body apart.  There's a diagram in the instruction manual.  Take it apart somewhere that is conducive to not losing small parts.  I usually work on a white towel on the floor.

Edit:  Now that I know what you're shooting I have to admit limited familiarity with Spyders.  Here's my best recommendations:

1.  Before you do anything else (of course the air source and hopper is already off and their isn't a paintball in the chamber) remove the grip frame.  I had an F2 Illustrator that the bolt got stuck forward on because the frame screw spacer deteriorated and the screw ended up working its way into the marker to the point where it interfered with the bolt.  You want to be positive you are not dealing with a similar problem before you apply force as a solution.

2.  Remove the barrel and inspect the front bolt as best possible using a flashlight.  Remove any paint/shell residue as best you can.

3.  Assuming the upper receiver contains no electrical components (as I said, I'm not that familiar with Spyders), spray/run water into the upper bolt area.

4.  After each step, you should check if the bolt will move.  If, after all of this, it still won't move, it is time to apply the minimum force necessary to make it move.