hello Gowri,

The hall ticket of 12th class is important document to be submitted for MBBS application and you have lost that.The options you have now is to submit/scan a xerox copy of the hall ticket if you have one or you can download the hall ticket again from the official website or write a letter to your college and ask them for a copy of your hall ticket.If you have uploaded any of the copy of hall ticket anywhere then you can download it from there. You can also give your hall ticket number for generating the hall ticket for you in your college.

These are the only options you have. 

hope this may help you.