It would be helpful to know more about the steps you followed, what you added and the quantities of what you added. The pH and SG at starting are also very important especially when you are making a DIY wine instead of a kit.
The Yeast may have exceeded it's max Alcohol limits, run out of nutrients or the must may be too acidic or to alkaline. The latter condition can lead to bacteria infections so if you have a pH meter or TA test kit, now would be a good time to use them.
For future reference, even with kit wines, it pays to keep good records of what and when along with all readings AND readings before you start are far more important than readings at present. (You can always to take a reading to determine current conditions.) With wines, if you don't know where you started, you don't really know where you are going. You can always go take a new reading "In process" but without those starting point readings it becomes more guesswork to solve problems.
By the way Blueberry based wines are notorious for being highly acidic and pushing yeasts beyond their limits in terms of acid.