Q: Can I find copy of my receipt of my handset with reference to serial no.of handset?

Hello rajthakur11,

Thanks for using Apple Support Communities. 

I understand that you'd like to get a copy of your iPhone's original sales receipt.

It's best to contact where you purchased your iPhone, and request a copy of the receipt. Visit an Apple Store, call 1-800-MY-APPLE, or find a reseller.

Additional information can be found in the article Keep your receipt after you buy an Apple device.

Best Regards.