Hi Donrhummy,
Thanks for the suggestion, but the exact problem now is, I am using a wp plugin called as Jquery Validation for Contact form 7, now this plugin helps me to validate the phone fields as well as other fields just by installing the plugin, but the plugin doesn't have a code to validate a name field for characters only. Since I am using this plugin, the code in this link http://blogs.lizardwebs.net/2012/03/a-solution-for-contact-form-7-phone-field/ wont work even after altering.
Do suggest me if any other options are available for the same...