joyous, joyful, joy, jolly, jovial, jammin, jaunty, juicy :]]]
wonderful, whimsical, witty
Words beginning with you are limited to forms of you, youth and young. If you mean "Happy words beginning with a U sound," perhaps you refer to euphoric.
1. Happy 2. Glad 3. Joy full 4. Cheer full 5. Boisterous 6. Gleeful 7. Gay 8. Bliss full 9. Content 10. Jolly 11. Delighted 12. Ecstatic 13. Merry 14. Jubilant 15. Thrilled
be, beg, big,