Hi @gauravsh8790,
You could use an install script with something like this:
$installer = $this;
$installer->startSetup();
$entity = $installer->getEntityTypeId('customer');
$installer->addAttribute($entity, 'your_new_attribute', array(
'type' => 'text',
'label' => 'Your New Attribute',
'input' => 'text',
'visible' => true,
'required' => false,
'adminhtml_only' => 0
));
$forms = array(
'customer_address_edit',
'customer_register_address',
'customer_account_create',
'customer_account_edit',
'checkout_register',
'adminhtml_customer',
'adminhtml_checkout',
'adminhtml_customer_address'
);
$attribute = Mage::getSingleton('eav/config')->getAttribute($entity, 'your_new_attribute');
$attribute->setData('used_in_forms', $forms);
$attribute->save();
$installer->endSetup();
Make a backup before execute the install script.