MD5 (Message-Digest algorithm 5) is a widely used cryptographic hash function with a 128-bit hash value.
An MD5 hash is typically expressed as a 32 digit hexadecimal number and is a one-way algorithm, that means with a MD5 code you cannot go back to the original string.

MD5 output has also a fixed length, no matter how long is the source, and is also univocal: there is very low possibility in fact to have the same result from two different strings.

You can find however some useful tools on the net able to decrypt a MD5 Hash. The ratio below is really simple: these sites have stored a large number of keys linked to their origin source: if your MD5 is present you will have then decrypted your code.

Here below some useful links:

http://md5decryption.com/

http://www.md5oogle.com/