If you cannot start QMF, there are several common fixes:
Check that the DB2 database is initialized and working properly. If all users are getting a type of ADMxxxx message upon start up, check that the base GDDM product is working correctly by running the GDDM IVPs.
If any DSN (DB2) and ADM (GDDM) error messages appear, look them up in DB2 QMF Messages and Codes.
Users should still look on the screen for more messages, and in DSQDEBUG and Q.ERROR__LOG for more information. If there are no other messages, have the user try to run the TSO command PROFILE MSGID WTPMSG and restart QMF.