Can anyone recommend a Korean drama which will make you cry?
Ugly alert- It won't make you cry all the time, but it will make u cry at certain points. 
See this review for more info: http://koreandramareviews.com/year-end-review-2013...
Take from the review above:
"Let’s go through the drama checklist:
Birth Secret?–Nope!
Amnesia?-Nope!
Super Evil Mother In Law?–Nope!
Evil Step-Mother?–Absolutely NOT!
Love Triangle?–NOOOOOOOO!
Dysfunctional Family?–Nope!
Devoid of Romance?–Nope!
Piggyback Scene?–Several
Bromance?–BIG TIME!
Thanks but could you guys recommend one who doesn't contain so many episodes? Maybe less than 20 episodes
49 Days
I Hear Your Voice
Kill Me Heal Me
Love Rain
Pinocchio
The Bridal Mask
The Moon That Embrace The Sun
I Miss You
The Princess' Man
Two Weeks
God's Gift
Secret

They're not gonna make you cry in every episode but they all have their one emotional story =)
If you'd like to watch movies to I'll recommend you some that are gonna make you cry a lot:

Miracle in Cell No. 7
Silenced or The Crucible
A Moment To Remember
A Werewolf Boy
Always
My Briliante Life


Thanks Melany I'll try some of them =D
the moon embraces the sun that will make you cry hard 
Can You Hear My Heart  - not only does it make u cry but its an amazing story very amazing ,   im gonna copy paste the plot 

Bong Woo-Ri (Kim Sae-Ron/Hwang Jung-Eum) was a bright 9-year-old girl, but she didn't have a name or a father. Her mother was also deaf. Nevertheless, there were good people around her like Bong Young-Gyu (Jung Bo-Suk) - a man who loved her mother and was also mentally deficient. The Young-Gyu lived with his elderly mother and his son Bong Ma-Roo (later played by Nam Gung-Min).
Bong Ma-Roo was an honor student who was insecure about his foul-mouthed grandmother and his mentally deficient father. To make matters worse, his father married a woman who was deaf. Meanwhile, 9-year-old Bong Woo-Ri was elated that she finally had a family and a name. Tragedy soon struck when a fire occurred in a factory where their deaf mother worked. Their mother died in the fire and their father was taken into police custody because of a frame-up . Ma-Roo left his sister and said he would come back. Now, Bong Woo-Ri, her grandmother and father awaited his return. Meanwhile, Dong-Joo (Kang Chan-Hee/Kim Jae-Won) lived with his grandfather, mother and stepfather. His grandfather owned the company "Yoo-Kyung," but the company was run by the step-father due to the grandfather's bad health. By chance, Dong-Joo met Woo-Ri. He promised to teach her how to play the piano. To keep his promise, Dong-Joo attempted to sneak out at night once. During this time, he saw his step-father allow his grandfather to die. An accident then occurred that resulted in Dong-Joo permanently losing his hearing. At the funeral for his grandfather, Dong-Joo's mother learned that her husband cheated on her and even fathered another child. Dong-Joo's mother also learned that the other child was Bong Ma-Roo. The mother then hid Dong-Joo's loss of hearing and took him to live overseas. For revenge, Dong-Joo's mother also took Bong Ma-Roo with them. While living overseas, Bong Ma-Roo changed his name to Jang Joon-Ha. Dong-Joo also learned how to read lips and, because of this, could act as someone with normal hearing. Everything was set. The three of them returned to South Korea and Dong-Joo now attempts to return the company to his mother and exact revenge upon his stepfather ....
90 days time to love is probably the saddest one I have seen.
golden rainbow is also pretty sad.
angel eyes is also another good tear jerker

those three are consistently sad each episode

a lot of people recommend the winter the wind blows, but I couldn't get into it. I might go back and rewatch it and try to finish it out. Same thing with stairway to heaven and tree of heaven.
Sirius, It's only 4 episodes, and so sad. :) I loved it. 
Scent of a Woman. 
Stairway to Heaven.
Sorry I love you.
Scent of a Woman
Who are You (2013)
Cruel City
The Moon that Embraces the Sun
Empress Ki (I know it's longer, but it's got sad parts from the beginning)
Bridal Mask
Secret
A Werewolf Boy (not a drama, but still heartbreaking)
It's Okay, That's Love (happier drama, but it's got the feels too)