You're a kdrama lover so you know already that in kdramas tears and laughs are offen mixed altogether. Whenever I need for a change of mood I rewatch You're Beautiful or Sungkyunkwan Scandal. First half of My Girl it gives you a big laugh too. Very funny kdramas with happy endings are:
Protect The Boss
Rooftop Prince
Hyena
Fugitive: Plan B
Unce Upon a Time in Saengchori
Smile, You
Soulmate - not really a crazy comedy but with a good feeling
Marrying The Mafia 1,2,3,4 and 5 - movies
For bad days better than dramas are sitcoms like Unstoppable High Kick - there are 167 episodes, 30min/ep but there's no need to watch it till the end since it's not really a story line, just enjoy the funny moments and the cast : Jung Il Woo, Kim Hye Sung, Kim Bum (BOF), Park Min Young~~
I hope these will be helpful