Hi Rajesh,
sometime it happens that we start MDM server and we do not look to the database
same issue i had.
check that your maxdb is working
command-> db_state
check that eveything is fine in db
command-> info state
i had this issue, and can you please check logs of maxdb, if logs were full and take backup of logs and database and then try to run to up your database
command-> db_online
and then start MDM
Thanks and Regards,
Murtaza