Is there any way to recover saves?

I was trying to do The new achievement, “The Rarest Specimen” I saved and started up a new game, but accidentally I quicksaved too much and my progress with the hat is gone, it doesn’t show up in the “Load game” menu. So, is there any way to bring those saves back?

No need to recover the save.

You could check if an older save is still present in Steam Cloud, where you can download it:

https://store.steampowered.com/account/remotestorageapp/?appid=362890

If Black Mesa is still running, don’t quit it yet, or the older saves will likely be deleted/overwritten in Steam Cloud.

This only applies if Steam Cloud synchronization is enabled for Black Mesa (which is it usually is unless you disabled it.)

Thanks to both of you guys.