For my own development I frequently rotate between different app servers and different versions, Tomcat, JBoss AS, Glassfish, trouble is when you work with one for a while and then go back to one of the others, you forget key things, like what your admin password was when you last installed/configured a server.
Whatever the reason, there’s a few different approaches to working around this issue with Glassfish, like creating a new domain and copy files from the old to the new, but this question on superuser.com has the best lifesaver response ever… this file has a backup password that you can use for your admin account, even if you have no idea what your original password was – just copy the value from this file:
glassfish3glassfishdomainsdomain1configlocal_password