I assume that you want to convert it into a WIF key, so it can be used in a wallet - this is what http://offlinebitcoins.com/ can do for you, one after another ...
There are seven steps behind, as explained here: https://en.bitcoin.it/wiki/Wallet_import_format.
There is the bitcointools and botg (bitcoin of the grid: https://bitcointalksearch.org/topic/bitcoin-off-the-grid-botg-secure-savings-script-v011-23081).
These are shell scripts running on unixoid OS, with a bit fiddling around (it has base58; sha256 and ripemd160 can be coming through openssl), so you'd quickly get what you are looking for.
I am not aware of a Windows shell script suite.
$ echo -n 'hexstringhere' | xxd -r -p | sha256sum -b