If none of those above solutions work, it might be possible to use emergency login into the system. Then setup your own username and password in the management portal once in.
1. Stop cache instance.
2. Open windows cmd as "Run as administrator".
3. Browse to the bin directory inside the directory where you installed cache.
4. use the command
ccontrol start <instance> /EmergencyId=<username>,<password>
Where instance is the name of your Caché instance, and type any username and password.
ccontrol start MyCache /EmergencyId=Eugenia,52601
Try to login using that and then setup a username and password and then restart Caché to login via the newly setup username and password. You can read more under "Emergency Access" here: