I have been asked to change my username details for my router DLink wireless ADSL 2640B how do i do this

Try D-Link Support, may be a firmware issue? Here: http://www.dlink.com/us/en/home-solutions/connect/modems-and-gateways/dsl-2640b-adsl-2-wireless-g-router-with-4-port-10-100-switch

YES THATS TRUE. TO CONFIGURE THE ROUTER. NEED THE PPPOE USERNAME AND PASSWORD FROM THE INTERNET SERVICE PROVIDER. VPI AND VCI SETTINGS.
..THEN ACCESS THE ROUTER PAGE
..GO TO ADVANCE SETUP PAGE.
..THEN LAYER2 INTERFACE
..CLICK ADD
..CONFIGURE THE SETTINGS.
..POWER CYCLE THE NETWORK.

If you forget the password, you need to reset the device to the factory default settings. In that case, all configuration settings of the device are lost then you need to reconfigure the router,
To reset the device to factory default settings, follow the instructions from this link,http://global.dlink.com.sg/site_support/DSL-2640B/Manual/DSL-2640B_manual_v2.pdf

Hope this helps.

go to ftp://ftp.dlink.se/Products/dsl-products/dsl-2640b/Documentation/DSL-2640B_Manual_v10.pdf for detailed instructions

Since your using an adsl modem, possible that is a problem with your adsl box or your adsl line. I would suggest you to call your ISP so they can further check your line and also your adsl modem .

You may also contact dlink so they can perform a firmware update to your modem , below is the link for their website.

http://www.dlink.com/corporate/worldwideoffices/?redirect=%2fdefault.aspx

cheers,
KA

1. Install Router Commander
2. Go to ADSL tab
3. Fix reported problem

check if you have the correct username and password for the ADSL line entered into the router, if its correctly entered then reset the router once it should ideally pich up the ADSL Connection.

Follow
anurdh65 solution...........

If you forgot your password, you must reset your modem.

Note: This process will change all your settings back to the factory defaults.

To reset the modem:

Step 1 Locate the Reset button on the rear panel of the unit.



Step 2 With the modem powered on, use a paperclip to hold the button down for 10 seconds.

Step 3 Release the button and the modem will go through its reboot process.

Step 4 Wait about 30 seconds to access the modem.

After restart the modem you can use default username and password (admin/admin)

For further help you can check the link below

ftp://ftp.dlink.com/Broadband/dsl2640B/Manual/dsl2640B_Manual_100.zip

First I will need to know the type of ISP service you have, T1 - DSL - ADSL - CABLE - etc. And the connection type, STATIC IP - DYNAMIC IP - PPPOE - etc. BPCS