First of all, make sure that you can connect to DeskNow via SSL using the default keystore. A copy of the original keystore is in the file C:Program FilesDeskNowconfkeystore.default . Just copy it to keystore and restart DeskNow.

If you still cannot access DeskNow via SSL, this is likely a connectivity problem. Check that the port number is correct (443 by default, unless changed in the config wizard) and that there are no firewalls blocking it. Also note that DeskNow Lite will let you access the login page via SSL.

If, on the other hand, the default keystore works, maybe there is a problem in your keystore. One possibility is that you used a different password from the default 'changeit' when generating the key, but then decided to change it back. In this case, note that there are 2 passwords protecting a cert key: the password for the keystore and the password for the key in the keystore. They must be the same in DeskNow (Tomcat).
To reset both of them to the default value, use these commands (in desknowdatassl):

"C:\Program Files\DeskNow\java\bin\keytool" -storepasswd -keystore httpkeystore -new changeit

"C:\Program Files\DeskNow\java\bin\keytool" -alias tomcat -keypasswd -keystore httpkeystore -new changeit

then run updateHttpKeystore.bat and restart DeskNow.

In both commands you may be prompted to enter the old password of the keystore or of the key.