Ghost_Stalker,
I regret to be the one to tell you this, but unless you backed up your certificate (see
here; note that a reformatted computer is another computer for all intents and purposes), there is nothing you can do about it now. That, after all, is the whole point of encryption.
The only exception would be if your computer was a member of an Active Directory domain -- in that case, your domain administrator may be able recover the file. Otherwise, the fat lady has sung.