My daughter is having trouble adjusting to life without her mother

It has been 19 months since my wife passed away yet my 14 year old daughter still has not recovered from her loss.  She locks herself in her bedroom for long periods of time.  She shares very little with me about her day let alone her life or her feelings.  I just don’t know how to help her.  Has anyone else had similar experiences?  If so…please tell me what you did about it.