So I have been running this registry command in my setup:

[-HKEY_CLASSES_ROOT\CLSID\{540D8A8B-1C3F-4E32-8132-530F6A502090}]
@="Language bar"
"MenuTextPUI"="@%SystemRoot%\\System32\\msutb.dll,-325"

Now I have a user that wants to use it. Does anybody know how to re-enable this setting?

I have tried thru Regional Setting with no luck...

Your registry command removes the entire Language Bar CLSID tree, so you'll probably need to re-import it. FWIW, here's mine:

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\CLSID\{540D8A8B-1C3F-4E32-8132-530F6A502090}]
@="Language bar"
"MenuTextPUI"="@%SystemRoot%\\System32\\msutb.dll,-325"

[HKEY_CLASSES_ROOT\CLSID\{540D8A8B-1C3F-4E32-8132-530F6A502090}\Implemented Categories]

[HKEY_CLASSES_ROOT\CLSID\{540D8A8B-1C3F-4E32-8132-530F6A502090}\Implemented Categories\{00021492-0000-0000-C000-000000000046}]

[HKEY_CLASSES_ROOT\CLSID\{540D8A8B-1C3F-4E32-8132-530F6A502090}\InProcServer32]
@="C:\\WINDOWS\\system32\\msutb.dll"
"ThreadingModel"="Apartment"

Thanks, that worked.