Search toggling the visibility of bend lines in the solidworks knowledge base.
Solidworks sheet metal drawing show bend lines.
Go to the view drop down menu or the view heads up menu and select sketches.
Expand the flat pattern feature right click bend lines and select show or hide.
No bend lines but bend notes are show then your sketches are more than likely not set to view.
You can control the precision for sheet metal bend line notes in tools options document properties tables bend.
In the featuremanager design tree expand drawing view to show the flat pattern feature.
Hiding the bend lines also hides the sheet metal bend notes.
This toggles the visibility of sketches and if it is off the bend lines sketch will be hidden the second method i used was to expand out the flat pattern in the feature tree and find the sketch bend lines2 could be other numbers shown.
Show or hide bend notes.
Displaying solidworks bend lines the first method i tried was to go to view sketches.