Have you tried double clutching into 2nd? If the synchro is bad, this will let you into the gear.
1. Let off the throttle, press in the clutch, and shift the "stick" to neutral.
Let out the clutch.
2. Bump the throttle to make the engine "blip". Sometimes in my MG I'll press in the accelerator all the way to the floor for a fraction of a second.
3. Press in the clutch.
4. As the engine speed decreases to match the transmission speed, throw the stick into the next lower gear. Since you actively "matched the revs", it should fall right in!
5. Let out the clutch. The downshift should have been as smooth as butter!
From my old Honda days (it was a real issue in the H22a, or Prelude, transmissions), sometimes the teeth of a gear can "mushroom" out at the dges which will be hardly noticable at all until the gear can no longer engage because the edges are too rolled over.
As for a broken shift fork... I don't know what those symptoms are and I would imagine it would effect more than just second since it is a major component in the tranny.