Arts ( Fine / Visual / Performing )

Hi,
Bollywood music industry is totally a different platform which is based on your talent, luck and network. To become a playback singer, you don't need or require to have a degree or Diploma.
So, I would suggest you to search and pick an esteemed music guru who can groom your talent. Do riyaz and practice regularly. Prepare your demos of latest trends which can present your talent and quality of singing.
Watch singing shows on tv and attend the singing shows, events. Share your audios and videos when asked on TV shows. Try and participate in singing shows. They are the best platforms for you from where you may get chances to enter in Bollywood.
There is no such short-term course that can help your purpose.
if you can afford it, it will be great if you join AR Rahman Music Academy or Suresh Wadkar School of Music.
Hope it helped you.