Has anyone gone back to work and your job duties have changed?

I work in pharmacy and I've been in charge of a certain task for the last 2 years. I came back to work this week and was informed by a co-worker that it's no longer my job. They gave it to the girl I trained to do it while I was on leave. My boss didn't tell me until 3 days after I found out. The reasoning is that my job was changed to be in another department. The rest of my job stayed the same and they have not given me another job that is similar to what they gave away. All I got was "I'm sure you will find another role in the pharmacy".

Man I really looked like an idiot when I was told it's not my job anymore. I think I must have been the last to know. My boss is aggravated that the person told me before her. She said she waiting a week to tell me. I have never felt so betrayed and lied to in my life.