Dreams or visions of a mummy reflect death and rebirth, past life of things that have not ended, not living or dead. The mummy reflects the inner part that dies, you close something off in your life. You are consciously letting go so that you can start over.
Another explanation is that it is now really time to let go of the past, and for that you have to gather forces and seek to move on. Yet another explanation is the reflection and projection of your traits, fears, problems and emotions on the mummy and then for that which has died of that which you must let go.
An important addition is the mummy can also be associated with death, burial etc. Death tells you everything about the death and rebirth of new things, opportunities and possibilities, awareness of the fact that there is always a new situation how difficult as it may be.
An alternative explanation is that a sarcophagus or mummy from ancient Egypt never had past lives; looking for spiritual answers, insights and knowledge of the past. An additional explanation is that there may be a past life and / or a desire for a more spiritual, conscious life. Yet another explanation is the connection with the initiation or higher dimensions and / or gods and the universe, stars and extraterrestrial.