There has been a series on EWTN called Living the Discerning Life which features Timothy Gallagher, OMI, a Missionary Oblate of Mary Immaculate. I have found the parts of the series that I have been able to watch very helpful in explaining what St. Ignatius of Loyola would call Spiritual Desolation. Fr. Gallagher talks about using Ignatian Spirituality to understand these natural phases of Desolation and Consolation in our prayer lives.
Fear not, Spiritual Desolation is natural and necessary for deepening of our faith.
Another thing to research that I have seen discussed on Women of Grace is the Dark Night of the Soul – St. Therese of Liseaux, St. John of the Cross, and Blessed Theresa of Calcutta experienced Spiritual Dryness and periods of marked desolation. There is lots of material to read about that.
May God Be with you – and all of us – on our spiritual journey.
I forgot to mention that the key is to stick with your prayer life - stay with your routine. St. Ignatius would say stick to it even down to the minute. If it is the evil one causing your desolation, recognizing the dryness and staying with your regimen in time will bring you back to consolation.