According to the internet, the lock should have the normal operation for a combination lock. The combination has four numbers and is dialed as follows
five turns clockwise to the first number
four anti-clockwise to the second
three clockwise to the third
two anti-clockwise to the fourth
then turn clockwise about half a turn until it opens
If that doesn't work then there is obviously something wrong with it. I would call a locksmith if you want it fixed.
There are websites that will give you more information on the safe, but I doubt you will find information on how to fix it, and if you did it would probably be too complex for someone who didn't have lots of knowledge on locks. I don't think safe work is something for newbies like you and me.
A google search can take you to pages that will give info on the lock like this one:http://www.codesmiths.com/shed/locks/manifoil.htm
Don't take anything I say as a definitive answer though, I'm a newb compared to most people here, and there are lots of people more experienced than me.