Yes, you can file an RTI application to know the procedure to correct the marksheet and you can ask for attendance details/registers as per the records for the concerned examination.
Delhi University established in 1922 as a unitary, teaching and residential University by the Act of the then Central Legislative Assembly. . Hence, the University is a "Public Authority" as per Section 2 (h) of the RTI Act 2005 and comes under its ambit.
To know more about the procedure to file RTI for Marksheet / Certificate Verification, please refer https://onlinerti.com/how-to-file-rti-online-for-center