Mary stood outside the tomb weeping tears of confusion and consternation. She cried because all her certitudes failed. Logically, Jesus who was laid in the tomb should be in the tomb but He was not. Her immediate conclusion was that some people "have taken my Lord away" (Jn. 20:13).
Mary did not know two things - where Jesus was and with whom she was speaking. Jesus' first question "Why are you weeping?" was similar to the angels' but His second question moved beyond theirs. His second question, "Who are you looking for?" reiterates the first words spoken by Jesus in the opening chapter (1:38).
Mary did not see Jesus because she did not really seek Him. She sought a missing corpse, not a Risen Lord. Mary saw and knew in the ways the world had taught her to see and know. Thus she saw only a gardener, not Jesus. Even in the face of the Risen Jesus, Mary still asked "where" and "who". It was only when Jesus' voice broke through the ways of the world that Mary knew who it was that spoke with her. She then knew where her Lord was.
Dearest Lord, help me believe though I have not seen You.