At the moment you don't know why this happened. There are many possibilities:
- Someone who hates you got the message and ignored it.
- Someone got the message, wrote it down, but forgot to give it to you.
- Someone got the message, was on his/her way to your desk to deliver it, but then got interrupted and forgot.
- Someone got the message and sent you an e-mail, but due to some glitch the e-mail didn't get delivered, or the user was offline, or some such.
Upsetting as this is, do you want to go in angry and jeopardize your job over it?
It would be best to start by assuming it was a mistake rather than a deliberate decision by anyone. If you feel the need to investigate nonetheless, make it as casual as you can. Perhaps talk to your boss: "It's strange, the hospital said they left a message here, but somehow I never got it..." Give them a chance to explain.
By the way, I'd say the hospital screwed up too. They didn't talk to you, so they didn't have any way of knowing whether you'd gotten the message. At least they could have left you the message at home as well as at work.
EDIT: One thing that just occurred to me:
Due to HIPAA, the hospital was probably not at liberty to say much of anything about why they were calling. They certainly couldn't mention your husband's condition, and they might not even have felt it was legally proper to mention his name.
It's quite possible that all they said was something extremely generic like "Please have [regina] call [XYZ Hospital] as soon as she can." It's likely that the people you work with quite reasonably had no idea the message had much importance or real urgency.