You probably got the premise if you've heard anything about Yesterday at all, but if you haven't, I would recommend that you put this movie on your watch list right now, and otherwise stop reading. (Don't read the fine print on the DVD box over there on your right either.)
I think it would be more fun to watch it if you didn't know the premise ahead of time.
Still here? Well, fine. I knew the premise, and I had a good time anyway.
Jack is an aspiring songwriter/musician, but his writing talents are at best mediocre. He's decided to give up his aspirations when an inexplicable glitch in reality, paired with getting hit by a bus, catapults him across the universe (see what I did there) into a slightly altered reality. The big important change: the Beatles never existed.
Out of the hospital, Jack discovers this while playing "Yesterday" for his friends. Who are gobsmacked by his hitherto-unknown genius, and don't know what he's talking about when he tries to credit the Fab Four.
And after a number of comic missteps, his knowledge of old Beatles tunes paves his way to pop superstardom. But can he honestly coast on someone else's talent like that? And what about his loyal manager, Ellie, who has loved him for years? Will she be left behind in his old life?
OK, it's sentimental and gooey. But still…
If you get the DVD with the alternate ending, I suggest you check that out. I liked it better than the actual ending.