Rediff.com India — my rediffmail account hacked

Address:

Bangalore, Karnataka

My [protected]@rediffmail.com is hacked but as of now able to access.
The hacker is demanding bit coins of 500 dollars .
This is my personal account and the hacker sent a mail from my account itself to prove that my account is hacked
He says my data and contacts would be destroyed..
I quickly need help before my access gets stopped and black mailed further.