The question is whether the audio is in the recording. If it isn't, then there is nothing to recover
What can happen is that the audio is recorded, but whatever you are using to play the recording doesn't recognize the audio. This is NOT common, and from what I've read usually involves someone doing something custom in the recording setup
I am NOT saying this is what happened, just a suspicion on my part that during the recording session, Audio was set to be captured. Either Advanced Audio Properties changed so you could listen (Monitor) but not Output (to stream/recording), and a video source was captured (ie the screen) but no audio source was configured??
Unfortunately, your scenario is the equivalent of asking to hold a fish from yesterday and we aren't certain a net was set out. Determining if you did capture audio, or the right audio, won't be easy as there are numerous things to check. Per the pinned post in this forum, there are instructions on uploading the OBS session log from your meeting. There might be settings folks here can check to see if obvious issue..
