Hello！
I quit minecraft and accidentally refused to resume unsaved playback when I reopened it. How Do I get unsaved playback back back?

Too late now, but for anyone who finds this issue in the future:

if you accidentally told the mod to not recover a replay, here's how you can get it back for up to a day:

1. stop MC
2. go into the .minecraft/replay_recordings folder
3. find the folder corresponding to the replay (it should end with .del)
4. rename it so it ends in .tmp instead of .del
5. start MC again