Hi prathap7475,
You need to provide more information about what you are trying to do?
You need to decide if you are going to perform an inlace upgrade (which is where you use the same DB server and App servers and essentially uninstall 12.21 and install 12.53 on the same App server ) or if you are going to stand up new APP and DB server instances and then migrate and upgrade your projects from the olde system to the new one (we would recommend the second as it allows you the freedom to migrate project as time permits and it also allows for a safety net should something go awry during the migration/upgrade process).
You also need to verify that you system environment is supported on ALM 12.53 before attempting any migration as it may not be a supported environment ( http://eyeontesting.com/questions/4804/finding-latest-supported-environments-for-alm-qc.html ).
Hope this helps.
Dan