This might help.

Remove all the listner services from the service manager.

In the registry HKEY_LOCAL_MACHINE/SOFTWARE/ORACLE create a string named TNS_ADMIN with value as the full path name where listner.ora file exists
Like "H:\Oracle\Ora81\Network\Admin".

Create a new listner by running lsnrctl. ( ur path should be proper if u have 2 or more oracle homes).

After the listner service has started, see if the proper listener.ora file is getting pointed to or not. ( can check this using the status option at the lsnrctl prompt. )..

Try connecting to the database after this...this may help as this was the error I was getting when doing a migration and the above procedure did solve the problem.