If the radio is read-protected...
Your only options aside from having (or guessing) the password are:
1) Find your archived copy of the .icf file that is in the radio now, which you kept in a safe place... right? Reload the saved .icf file into the cloning software, and enable "transceiver data out" before cloning to the radio, or,
2) Write a new file and start over.
A new file created by the cloning software can be loaded directly into the radio. Different from other manufacturers, Icom puts the radio-specific tuning and alignment information in a separate "Maker Reserved" section that is not touched when you simply create a new file and write it to the radio, so a new one will work just fine.
Did you try 123456, 000000, etc?