I understand that you are unable to open Simulink and it is unresponsive. The initial troubleshooting steps you can attempt when facing issues of this nature are to restore your search path as a corrupt search path can often cause startup issues.
Here are the steps to follow:
Before modifying the search path, it is important to take a backup of your 'pathdef.m' file, which can be located by using the command:
Before proceeding, ensure that you make a safe copy of the file by copying it to a folder outside of your MATLAB path.
After taking the backup, please execute the following commands in the MATLAB Command Window to restore the default MATLAB search path and rehash the toolbox cache:
After this step, please use Simulink to see if the issue occurs again. If the issue is resolved, then you may want to save the new MATLAB search path by executing the following command:
If this does not fix the issue, please contact Support.