Yamaha XT350 97. Went from mid 2nd gear to 1st without clutch (was an accident as im still learning). Rode the bike fine for the remaining 200m home, bike was fine or it seemed fine when I switched gears. after stopped bike wont go to neutral. Ive tried a few times, but it stays in gear.

Any Ideas please?

Hi Welcome to the YOC , it's normal to do an INTRO in the new members section before you ask a "How do I fix my bike" question. That way folks know that your probably not a one hit wonder.

Weak detent spring,

should be located under engine ,looks like another sump plug ,only smaller angled sometimes..