Hi, everyone

Soon it will be my best friend's birthday. As it is our 3-year anniversary, I wrote her a song. The problem is that I'm not a native speaker, so I'm not sure with some grammars in my song lyrics. Please help me with that. Any help will be highly appreciated. Thank you so much.

"My Best Friend's Smile"

Oh your smile, like the beautiful sunshine
It keeps this whole word alive and warm
Wonderful things in this world are here
As the sun is still shining

But someday if you really feel so blue
Never lose hope as you'll stop smiling
And how can flowers in this world bloom
If there's no light of your smile