it resets the router to factory default, and it wont have a WEP key, then just go to were SGT said :

Wireless>Basic Wireless Settings:
Mode: Mixed
Name: (put watever u want)
Wireless Channel: 9 is best

Save settings..

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to set pw..

Wireless>Wireless Security> Security Mode : WEP
Then put a 10 digit # in the Key 1: (Phone number is easier)

Click save settings..