Check if you still have the *.config_3D files in the following folder:
C:\Users\Your_username_here\AppData\Roaming\Altium\Altium Designer {Your_GUID_here}\ViewConfigurations
In the same folder check the configuration file named:
RegisteredViewConfigurations.ini
if you still have all the "views" registered.
The content should be like this:
[general]
LastCustomFolder=C:\Users\Your_username_here\AppData\Roaming\Altium\Altium Designer {YOUR_GUID_HERE}\ViewConfigurations\
[config_2dsimple]
Altium Standard 2D=C:\Users\Your_username_here\AppData\Roaming\Altium\Altium Designer {YOUR_GUID_HERE}\ViewConfigurations\Altium Standard 2D.config_2dsimple
Altium Transparent 2D=C:\Users\Your_username_here\AppData\Roaming\Altium\Altium Designer {YOUR_GUID_HERE}\ViewConfigurations\Altium Transparent 2D.config_2dsimple
[config_3d]
Altium 3D Black=C:\Users\Your_username_here\AppData\Roaming\Altium\Altium Designer {YOUR_GUID_HERE}\ViewConfigurations\Altium 3D Black.config_3d
Altium 3D Blue=C:\Users\Your_username_here\AppData\Roaming\Altium\Altium Designer {YOUR_GUID_HERE}\ViewConfigurations\Altium 3D Blue.config_3d
Altium 3D Brown=C:\Users\Your_username_here\AppData\Roaming\Altium\Altium Designer {YOUR_GUID_HERE}\ViewConfigurations\Altium 3D Brown.config_3d
Altium 3D Color By Layer=C:\Users\Your_username_here\AppData\Roaming\Altium\Altium Designer {YOUR_GUID_HERE}\ViewConfigurations\Altium 3D Color By Layer.config_3d
Altium 3D Dk Green=C:\Users\Your_username_here\AppData\Roaming\Altium\Altium Designer {YOUR_GUID_HERE}\ViewConfigurations\Altium 3D Dk Green.config_3d
Altium 3D Lt Green=C:\Users\Your_username_here\AppData\Roaming\Altium\Altium Designer {YOUR_GUID_HERE}\ViewConfigurations\Altium 3D Lt Green.config_3d
Altium 3D Red=C:\Users\Your_username_here\AppData\Roaming\Altium\Altium Designer {YOUR_GUID_HERE}\ViewConfigurations\Altium 3D Red.config_3d
Altium 3D White=C:\Users\Your_username_here\AppData\Roaming\Altium\Altium Designer {YOUR_GUID_HERE}\ViewConfigurations\Altium 3D White.config_3d