In Blender how can I open a .blend file and revert the UI layout to default settings?

Solution 1:

I don't know if there is a direct way to convert the files so that the window layout converts to the new 2.5 layout, however this solution should accomplish what you want.

If you just start Blender with a new scene, then import the scene from your old file it should work.

1. Start Blender 2.5
2. Delete the default box, camera and light (It won't let you delete World yet), Just press a until everything is selected in the 3D view and then x to delete.
3. Press Shift + F1 to import from library file.
4. In the file dialog, find your old .blend file and click on it then click into the scene folder inside of it and select your scene. Then click on the Link/Append from Library button.
5. Now your old scene is loaded into the current working session. Just click on the X button next to the current scene to delete the current scene and you should see your old scene. You might want to rename this scene to just be Scene. You also may want to rename what is now called World.001 in your old scene to just World. This happened when you loaded your scene and there were two things called World

Solution 2:

There is an easy way for this:

Start a new file in Blender 2.5, so the default layout is active. Press Ctrl-O to bring the open dialog in front. Now deactive the checkbox "Load UI" in the left panel under "Open Blender File" and load the old file as usual. It will be loaded without any embedded UI layouts.