Hi, Gagan

It is not clear what you mean sometime 'create plan' option does not appear. Is it the same user who can see the create plan option today but cannot see it tomorrow?

Usually if only create plan option is missing and others such as create test case, create test script and so on are present, it is likely the admin hide it on purpose(can be done in qm's admin page)
If it happens to all create xxx options(create plan, create test case, create test script etc), it could be related to license or the user is not a member of the project.

Thanks