Installation. Good morning sir , iam unable to install auto cad 2006. when i click to install it

Question

Good morning sir , iam unable to install auto cad 2006. when i click to install it is saying that already installation is running .actualluy i have installed auto cad 2006 some 6 months ago.in that i have run the product and my expiry date is over because i had not activate the product.My friends are saying to format the computer and then install auto cad 2006.Plese kindly help me in this regard. Please send me information soon , iam in online. Thanking you sir