yep its not a capacitor at all ...capacitance can exist if same charge density is there for  opp charged particles

u can hav capcitance for a isolated conductor considering the other object(plate) to b at infinity.....

a capacitor is one with opp cahrged plates only!!! even when u construct a capacitor

assume u have a  positively charged plate first then an insulated one this plate induces a negative charge on teh insulated one...so positve charges got to the opp side of the insulated plate then they r earthed!

so u hav got opp cahrged plaates which form the capacitor....and u cannot hav two lik charged plates!

 rate if this is not bad....:)