Someone was deported 4 years ago for overstaying there visit visa by 6 years they have managed whithout a passport to get back into the country what can be done they are not a british citizen but have children in the uk?

They are "here" illegally - where is "here"? Many Countries post on AMHD.

I assume the OP means UK. Since you don't have sufficient info, it's hard to draw a line. People who were deported in some cases can immigrant visa if they are qualified in either one categories. Being deported does not mean a lifetime ban, except those who committed crimes.