I have a certificate object. How can I search and find the root certificate of my certificate from the root store?

Initialize a CertificateChain instance with your certificate. One you have the chain, call the GetCertificates method. This method returns an array of certificates. The certificate with the highest index is the root certificate [if it can be found].

doing what you said with a certificate in a smartcard doesn't work. the chain always have a "count" 1. No matter what you chooose as an additional certificate store in the certificatechain constructor.

But the thing is i can see its chain clearly in internet explorer's certificate view form.