Don't do things to your computer that you don't understand completely, a good guess is not good enough.
The most formidable law on earth is the the Law of Unexpected Consequences.
(Yes, God has laws too, but they are not formidable, they are reasonable).
Now to your problem...
If you indeed formatted your hard drive (or pc as you said), then you erased your hard drive and re-installed Windows.
Since you encrypted a folder in your former install of Windows, and formatted, re-installed.... well... that folder no longer exist and even if it did, your old password would not work anymore anyway as the security key to that file is long gone too.
You screwed up. Your folder is destroyed and gone.
Better luck next time.
Read my first sentence over and over again until you understand it.