Here i have an requirement that, we have a different users based on the categories and for every users inquiries will be assigned. Here every day i want to send the mail to them that how many inquiries was assigned to him and how many are in pending by the end of before day. May be the user have more than 10 items. All those items should be send through an email. what was the best practice to do it How can i implement this in the 2013 workflow.
Why not use a Task List for this; it has a built-in email that is sent to the 'Assigned To' person when the Task (or enquiry) is assigned to them. Check this guide for assistance.
The users will have the email in their inbox as a reminder. All tasks are visible on the Task List - if you set up a view to filter only on Tasks assigned to User A, they will see their own tasks.
Or if you want to customise a List then you might like to read this post for help on using Sharepoint designer to send emails.