Darn, hope you find her! It really does happen to all of us, eventually... Accidents happen.
Try laying down a line of baking flour/powder across each doorway and hallway and closet doors, and check every few hours to see if one of them has been disturbed. The flour will be dragged in the direction she went, and you can narrow down the area. In fact, the more flour borders you lay down, the easier it will be... it'll just be a mess afterward LOL.
The one time it happened to me, thankfully I still lived in a small and uncluttered apartment, so I found her within a few minutes.