Password in w-lan

In a home wireless lan with NETWORK MAGIC, access from the secondary computers to the files that are share-enable on the main computer is denied unless a password is provided. A password has never been entered.
The password of the router is not accepted.
All the most usual passwords (e.g. “admin”) have been tried in vain.
The so-called helpline of NETWORK MAGIC is of no help either.
Any suggestions would be appreciated