Suzuki 2 Strokes

So I was changing the transmission oil on my 550, and made I hope to not be a big mistake. I unscrewed the angled bolt out the bottom and the spring and detent came out? I put it back in the way it came out. But now it won't shift out of neutral up or down? Is this an easy fix? I can't find anything on it other than an exposed view. What does this do? Thanks

It's the gearchange detent screw, spring and plunger - items 18, 19, 20, 21 on the diagram. You didn't move the gearlever while it was out did you?
If not and you replaced all the parts, the gears should change.
Does the gear lever move or what?

The oil drain plug is the vertical one, not the one on an angle. You aren't the first to take the wrong one out.

I did not move the lever. Just pulled the parts said "crap" that doesn't make sense and put it back the way it came out.

Try turning the back wheel as you try and change gear, or start the engine so the clutch rotates.
Sometimes gears won't engage when the engine or bike aren't moving.

So I drained the trans again. Pulled the plug spring and plunger out and checked the orientation to the exploded diagram. I did put it back in correctly. The rod that it rides against had rotated. So I felt around with a pick and got it to turn. Reinstalled everything and I it is now shifting like before.Thanks for the help!

Great news.