tempranova

This plugin requires Bootstrap, and makes use of the Bootstrap Datepicker at https://eternicode.github.io/bootstrap-datepicker/.
This plugin creates a search area above comments on any post or page. Here, users can choose to enter a search term, enter a date range, or select an option of the recent past (Today, This Week, This Month) from a dropdown. They can also combine these options to search for terms within a certain time period. Please note, a selected “recent past” option will override a date range entered by the user.
The search uses AJAX to query your database for matching comments, and returns all of the relevant results in the comment area.
A term search searches both author names and comment content.

Comment Filtering

This plugin creates a Bootstrap interface that allows users to search within your comments by a search term, a date range, or the recent past.

ranapiyush1986

This plugin allows you to set datepicker,calendar on your posts and pages just in single click. Ability to change settings of calendar according to your requirement.
Importance
Using calendar,datepicker in posts and pages is little bit tricky to newly wordpress users because integration of jquery UI Calendar makes some jQuery confliction and time consuming task.So This Plugin help users to make their DATE Field more funky and stylish just in one single click,and also have power to user set their DATE Format setting according to their requirements.
Usage:
Once activated, make sure to configure the plugin in the settings menu with the one of the available options.
<ol>
<li>Calendar Picker</li>
</ol>
and finally, you’re able to change settings of calendar need to show on posts and pages. 
If You dont wants to use setting of calendar datepicker, you just only use “calendarpicker” as your class attribute the Default settings automatically applied on your field in one single click.
Notes:
This plugin for WordPress, the publicly available If you experience any problems with the plugin, feel free to contact me.
Please please please don’t forgot to rate this plugin if you found it works and useful for your blog.

Simple Calendar DatePicker

This plugin allows you to set datepicker,calendar on your posts and pages just in single click.

Comment Filtering vs Simple Calendar DatePicker