If you view a working ADSL Modem as a "service" you need to do your other work and you want the service to be provided in the least expensive way with the least amount of trouble, then I agree with the other advisers here, throw away the old modem and get a new one.
However, if you see it as a challenge to get it working and you are prepared to spend some time on it, try the following:
1. Start with a proper reset. Disconnect the telephone cable and the LAN cable, switch on the modem, verify that the red POWER light is on and RESET the modem. This is to ensure there are not some funny settings you have not set up properly. See thread below:
http://mybroadband.co.za/vb/showthread.php?t=205155
2. Follow the advice in the link below to set the basic settings, and then set the DNS servers. After all is done, save the new settings and reset the modem to activate the new settings.
http://mybroadband.co.za/vb/showthread.php?t=47405
3. Switch off the modem, wait 30 seconds and switch on again, to ensure you start with a new session with the latest settings.
4. The green DSL-LNK light will start flashing at irregular intervals while the modem is doing the power-on self-test and configuration setup. Wait until the DSL-LNK light is flashing at a steady rate of about 1 flash per second. Now plug in the telephone cable and wait for the modem to synch with the DSLAM in the Telkom exchange. This should happen in about 30 seconds and then the DSL-LNK light will stop flashing and will be permanently on.
This step MUST be completed with the green DSL-LNK light permanently on; otherwise the modem does not communicate successfully with the Telkom exchange and the ADSL link will NOT work.
5. If you cannot complete step 4, go to a friend’s house or anywhere where you can connect your modem to a working ADSL line that is configured for only 384kps speed. It just may be that the old Telkom modem is not fully compatible with all the signals used by the new high speed DSLAMs used for 4 Mbps lines. (Any comment on this from other users? Yes, I know it really does not make sense to connect this old modem to a 4Mbps line.)
6. Once the green DSL-LNK light is permanently on, switch on your PC and plug the LAN cable from the PC into the modem. After about 40 seconds, the PC network interface will connect with the modem and set up a DHCP IP address. Now, the green LAN-LNK light must also be permanently on. When you check the status of the LAN link on the PC, (right-click the LAN icon in the system tray) the IP address of the modem will be 192.168.10.100 and the Default gateway will be 192.168.10.200
7. The next step is to run Internet Explorer and check the Connection options to ensure that no proxy has been set for the LAN settings.
8. Now, try to connect to
www.google.co.za. If it connects, go and have a beer to celebrate. If it still does not work, throw the modem in the rubbish bin, then go and have a beer to help you forget about it and celebrate the holidays!