Hey there @CStables - I am so sorry to hear this happened. What a difficult day your team must be having! I empathize!

Firstly, I hate that I have to report that there is no way to revert back to previous event type settings in any case, to include availability. It will likely be very helpful to tell your team to take extra caution when editing event type settings for this reason - ensuring that any changes they click “save and close on” effectively and permanently delete previous settings - this includes deleting entire event types (they cannot be recovered).

That said, there is a way to reset all availability at the same time using Availability Schedules - this is how you can temporarily “turn off” all of your 160 event types while you work to fix the scheduled available hours for each, one by one. It should take you five minutes or so. I recorded a short walk through showing you how I would do this, as it is technically a workaround (if you were to simply ask “can I turn off all of my event types at once?” the answer would be “no” - but I am creative!). Please see the embedded video below! I do hope this helps, but if you have further questions I will be here to answer them! 

Edit: in the part of the video where I say to apply the schedule to all active event types, you see me selecting each box one-by-one and telling you it’ll be the most time consuming part. Great news, though! I am not sure where my head was when creating the video , but you’ll notice a “select all” button above the boxes in the dropdown - use this to select all event types, click “apply” and you’ll be good to go!