Welcome a past life. Accept the very first thing you see on the other side of that door as something from your previous planes of existence.
It might be something as abstract as the color yellow, or as clear and vivid as a much-loved child nestled in your arms. Take whatever you see as the foundation. Build upon it. Feel it. Hold the imagery in your mind and open up to it, accepting anything that arises in your mind.
You might find that “yellow” becomes a carpet. As you walk deeper into your vision, you might discover that yellow is sunshine spilling onto a carpet. Perhaps you’ll suddenly realize that carpet is in a London house…and so on.
You may doubt yourself at this point, but be reassured, you are remembering a past life.
Accept what you see. It will seem like you are inventing these images. Sometimes you are, and you must accept that as part of the process of trying to remember a past life.3 Ways to Remember Your Past Lives – wikiHow