You and "your buddy" bought bitcoin together and both of you two know the password too?
Can I take some legal action against my partner?
What valid proofs you have if the password was changed by yourfriend? I know, it's to strange while the wallet password has changed and your friend also disappeared (too much coincidence).
Why did you have to start with 1 BTC though?
Because
as that gives you enough capital to never make a loosing trade with they system of trading I have.