I used the encryption on my logs so i could have some privacy on our family computer, but i had a problem with some person, and i may need that convo log to show someone, i never added him to my contacts, he aded me, but when i went to open the convo the password didnt work, i dont know if it was because i blocked him at the end of the convo, or if i mispelled the password when i set it, but i need to know if theres a way to un encrypt it withot the password?

if you're running a version of plus! thats lower than 3.20.100, id have to say you're screwed...its been fixed in version 3.20.100 (the encryption log password problem) You might have just typed the password wrong, sorry for the troubles... you cant get them back

IMO these conditions:
he/she added you and you blocked him at the end of the conversation don't affect on how the encryption works.

The most possible cause is that you mispelled the password.

As the answer of your question, the answer is simply no. Sorry...

How about the other logs? Can you open them?
If you haven't changed your password, make another conversation (with anyone) and see if you can open the log.

thats the weird thing though, its the only log that wont open up, all the rest use the same password, but that one wont open

yeah im having the same problem, only 1 log wont open but i no i dient type my password wrong

Don't you have the logs anymore which MSN Messenger makes itselfs? They are not password-protected...