The grub command line shell affords you the opportunity to find out what has happened. But you need to take the time to learn how to use it. I think it would be well worth your time for you and for us. Then we know what happened.
You are booting to grub.
Q1: Is this in a secure boot environment for from a "legacy" configuration?
Q2: What did Windows do? Changed the name and UUID of a partition? Format your Linux partition? What has happened.
I have gone to not doing dual boot with Windows simply because they do not wish to play well with other OS.
Would a good solution be to learn how to dual boot from Windows using their boot loader redirection?
Have a lot of fun!
Tod