My daughter understands any material orally but does not when reading from a paper, what is the problem or diagnosis?

This reading disorder can be a form of dyslexia or attention deficit disorder. A licensed educational psychologist would be best to evaluate your daughter's problem & outline treatment. A department of neurology or psychology at a university hospital near you should be able to recommend a specialist.

Dyslexia which is a reading disability, her pediatrician should be able to help and connecting with her teachers in addressing it properly.