You need to speak to a lawyer about the legal aspect of this. Didn't you have someone inspect the house before you bought it? I mean besides the Real Estate brokers assertion that everything was okay.
How big a crack are we talking about? How long and how wide? How much more has the crack opened since you've owned the house?
Ron

yes, the Real Estate brokers hire the inspector for me and he said that was okie, actually they have about 3 crack in one wall, another 2 crack in other , 1 in one and 1 in other, when the crack reopen just about hair line but Enough for the water run throught it i spent 1 k so far to seal 2 crack but still have another 2 need to be done, and the crack run vertical , i asked the company who just seal the crack in my basement and they said i need to install some kind of sump pump and the drain system inside my basement and that cost around 6k ,
pls, help me anyone know about the law

You NEVER hire anyone recommended by a real estate agent, NEVER! They hire these "yes" men to minimize outside influences on the sale. How long do you think they would use these guys if they lost a commission on their report.
Next time hire you're own inspector.
I would get a few other opinions before I sank any more money into this with your current contractor. The best way to get educated is to speak to these guys. You will find that more then a few are not competant. If you hear the same diagnosis from a few of them, then that's probably what's wrong. Then you pick the one you're comfortable with. Check them through your local Better Business Bureau or what ever governmental agency monitors them. You might end up with the same guy.
The "waterproofing" industry, in my opinion, is one that is rife with con artists.
Ron

anyone can telll me how to install the water guard and the sump pump please, i don't think i can afford for 6 k to fix that, cause i call alot of man for foundation and seem everyone come up with different idea about that
please

When I first read this post I thought the cracks were in the floor. I also have a crack in the wall that leaked after every rain. Rerouted the drainage from the gutters, raised the grade at the side of the house and now it never leaks again. If you can remove the water, before it can enter the basement from the outside, you don't need any fancy drain work or crack sealer. Repairing the walls won't work if the water keeps pushing against it.

I had 4 crack in one wall and one crack on the other, 2 crack i leaking and fixed by woods basement system in missouri, also i had drywall crack vertical on every windown frame upstair of my house and one little crack outsite of my house on a brick wall anyone known that my house might sinking ?

Call a structural engineer and a lawyer. You have more problems than can be addressed here.
Ron