Your MATLAB's preference directory might be corrupted.
Delete the folder (you can know the location by prefdir command in MATLAB)
If your MATLAB version is R2019b, the directory is
C:\Users\XXX\AppData\Roaming\MathWorks\MATLAB\R2019b
where XXX is your account name.
After deleting this folder, then call MATLAB again. The folder will be created.