Cannot select anything but an edge highlighted in pink When I opened a project that was left for a couple weeks, I was stuck in the situation as shown in the picture, where I could not select any other vertices or edges other than the edge highlighted in pink. Even when I tried to click on the other components, it will somehow drag the pink edge and extrude weird faces. How can I solve the problem? Do I need to exit a certain "mode" to get rid of this?
In the screenshot I can see you have all of your object geometry selected, not just one edge: how?

Look at these numbers in the bottom right edge of the window:



they say that you have 251 vertices selected out of the total 251, and so on for edges and faces.

Your pink edge should be an edge with some "special" feature, likely a crease, as others said.