You have not given us much information to work with to solve your issue. Can you verify that ASDM is correctly configured on the ASA? Can you post the configuration for ASDM? And can you post the output of show flash to verify that the file you use for ASDM does exist in flash?
What IP address is on the PC that is attempting to use ASDM? How does this PC connect to the ASA? Can you post the part of the config where you specify which addresses/subnets/networks are permitted to use ASDM?
In my experience issues with ASDM are sometimes related to the version of Java used by ASDM and version of Java that exist on your PC. Can you post any messages generated on your PC when you attempt to use ASDM?
Here is a link that discusses issues using ASDM. I hope you may find it helpful
https://community.cisco.com/t5/security-documents/asdm-access-troubleshooting/ta-p/3122148
HTH
Rick
HTH
Rick
