I'm really not sure.... Which View Scheme is missing? I'm assuming that you just lost one of the default View Schemes (which can be deleted by selecting them and right-clicking and choosing Delete).
To create a new one, to replace your missing one:
1. Select Audio in the Tree (assuming you want to make an Audio View Scheme to browse your music files), then Right-Click and choose Add View Scheme.
2. In the Edit View Scheme dialog that appears, you can define the properties of your new View Scheme. If you are just recreating one of the defaults, you can easily pick from the Presets drop down. For example, the default Artist/Album View Scheme can be created by selecting the Album Artist (auto)/Album preset.
3. If you don't want to use any of the presets, you can create your own by clicking the Add button under the Step 1 section. Then choose Standard View Item and choose which field you'd like to show up as the first "Pane" when browsing. Click OK when you've chosen. Then, you can add another one that will show up as the second "pane". And so on and so forth.
4. Under the Step 3 section, make sure to check the top three boxes. Leave Filter in both directions unchecked for now.
5. Under Step 2, you can uncheck Auto-name and type in any name for the View Scheme you want. Otherwise, just leave it alone.
6. Click OK and you should have a new View Scheme in the Tree under Audio.
For more information on View Schemes and how to create and modify them, check in the Help file View Schemes topic under View Files and Libraries.