If a person never received a discovery after requesting it from your defense attorney charged convicted & sentenced after a 3 year case

I have never heard of a case being overturned, or a plea being allowed to be withdrawn, due to the defendant not receiveing copies of the discovery. If she was represented by the public defender, or possibly even by a private lawyer, and was in jail, then the public defender has a policy against giving people their discovery due to concerns that other inmates could get ahold of the discovery and make up stories about things the defendant said (to better their own situation).  However, they most certainly will have discussed the contents of the discovery with her. If she truly was never told what the discovery said, and IF there is something in the discovery that would cause her to have done something different than she did, it MIGHT be a basis for trying to re-open the case (withdraw her plea and start again). However, if that is allowed, there is no promise that the new outcome will be better than the plea she took orginally.  And such process can be very expensive to pursue.