No shift to 4th then no shifting at all

[mgolley]

I started with a new transmission a month ago, because I lost drive. Now a month later I lost the shift from 3rd to 4th. when I pulled over to check it out I couldn't shift out of drive. The gear shifter worked fine but trans wasn't moving. Then when someone was trying to shift shifter and I was watching transmission shift linkage it made a clank sound and freed from drive. Now I have full shifting range from park to drive but no movement in any gear. Please help! Not sure where to go from here.. Other than taking it to same mechanic again.....never going there, took a month to get my truck back!!
Thanks to all who answer.