A while ago something went wrong with my transmission.I was racing a Z28,shifted back to second,it made a nasty noise,but went in.( i didnt crash the gear,it went easy,so no force was used)

I cant shift back from 3rd to 2nd anymore,doesnt matter if i`am doing 18mph.
What could be the cause ?Did the selector arm bend,or the syncro just give up?

Please HELP ideas!

 

bent shift fork or mis=aligned slider, if it was your sinchro it would still go into gear but it would grind every time..