I have a frame file I've been working on for a long time, but today the 3Dsketch that everything is based off of disappeared from the feature tree. The sketch still exists since the features are entirely intact, and the 3Dsketch can be viewed by editing the features but still not accessed.
The first picture shows a previous version where the 3Dsketch is still there, while the second picture shows the current version where the 3Dsketch is not visable.
Any idea how to fix this? Any help is appreciated.