I have court ordered vistation rights with grand kids my ex-daughter-in law is keeping kids from me

If your visits are court ordered and you are not getting the children according to that order then you need to go back to court to have the order enforced.

Ex-daughter-in-law got custody of kids after one child was in major child abuse case, court ordered not to have any person of opposite sex in living together with kids a month later starts living with a boyfriend

Then someone has to take her back to court. For contempt and to possibly change the custody orders if she can't follow them.

Then she could lose custody of the child.
Someone needs to report her to CPS or file in court

I don't know where my grandkids are mother moved didn't provide address

Each investigater charges their own rate. You will just have to find a couple in your area to find out. The court will need that to properly serve her but you should look into lawyers in your area as well so you can get into court to get your visitation back as soon as she can be found.