This article teach you how to D-Linkto restore factory settings, as an example.
Step 1 With the unit on, place a paper clip into the hole on the back on the unit labeled Reset.
Step 2 Hold paper clip down for 10 seconds and release. (Note: Do not repower unit during this procedure.)
Step 3 The unit will reboot on its own. Once the WLAN light stops blinking, the unit is.
Resetting thedoes not the firmware to an earlier version. It will change all settings back to factory defaults.