Google prompted me to change my hotmail to a gmail. Made me do the same on my phone. Now my entire calendar disappeared. Help!

I have a Samsung Galaxy 7 edge. I was on my laptop, and google prompted me to change my sign in email, which was a hotmail address, to a gmail. So I did. This sent an alert to my phone. After I followed the prompts on the phone, all of the events on my calendar disappeared. I have contacted Verizon, Samsung, and Google technical support. The only thing I have now is birthdays and national holidays. None of my appointments or anything else I had in my calendar is there. I need this stuff. Can anyone help?