Summarise How a Game Master Can Recover From a Session That Went Badly

Bad sessions happen and they are almost always diagnosable. The question is whether you run the same session again slightly differently or identify what actually caused the problem. This helps diagnose the specific cause for each problem you experienced, prioritise what matters most to fix, design the opening of the next session to reset cleanly, and prepare concretely in the 48 hours before.

My last session did not go well. The specific problems were: {SESSION_PROBLEMS}.

Help me summarise what actually went wrong and how to recover:
1. For each problem described, identify the probable underlying cause (preparation, improvisation failure, player-GM communication gap, or another)
2. Rank the problems by priority: which had the most impact on player experience versus which is easiest to fix
3. Design the opening of the next session to acknowledge what happened without dwelling on it and create a clean reset
4. Give me the three things a GM can do in the [48 hours] before the next session to be better prepared for these specific problems

Do not tell me every session is a learning experience. Tell me what to do.