Unable to track tasks assigned to a user

Dear All,

ISSUE:

A user has 1000+ tasks in a his worklist.

Those processes are being raised by different users.

When I am trying to find the task in NWA using the userID  and setting all the  parameters  correctly.

Then the processes are not being retrieved. The search is not working for this scenario.

QUESTION:

Is there any other way we can find the processes in which a task is being assigned to a user and Cancel/Suspend the process.

So that the task goes away from his worklist.

Please share your ideas.

Thanks,

Shyam