Missing block file names

The .aup file for an episode is missing block file names - the episode is too long to add them in manually - there 1300 of them or so - all there, but all out of order

Which version of Audacity are you using? (Look in “Help menu > About Audacity”.)

If the block file names do not match the AUP file, then the project is seriously broken and may not be repairable. There is some information here about recovering broken projects (http://manual.audacityteam.org/man/recovering_crashes_manually.html), but please note that if the project is beyond repair, then you could just be wasting your time trying to fix it - better to find the cause of the problem and ensure that it does not happen again.