"I have deleted an important mail, please tell me how to recover the same?"
All the emails that you delete are stored in the 'Deleted Mail' folder and are emptied by the Rediffmail system once every 24 hours. Emails are also deleted from the Deleted Mail folder if you click on the "Empty Deleted Mail Folder" button.
Please check if the emails have been deleted from the 'Deleted Mail' folder. If the mail is deleted from the 'Deleted Mail' folder then the mail cannot be recovered.