Well, you have the DSST Fundamentals of College Algebra, and the CLEP College Algebra that cover the basics. I here that the DSST version is easier, though I must confess that I have taken neither. Perhaps others on the forum can provide more information on these exams.

My advice is to chalk it up to experience, and keep pushing forward. Your prior studying need only go to waste if you allow it to. Look at it like this. You've already been studying for the DSST or CLEP version.

Better luck next round.