I heard that some TP-LINK router IP address is 192.168.0.1 or http://tplinklogin.net. Maybe you can have a try.
1. Please make sure your computer and router, modem are connected correctly, modem to the WAN port, computer to one of yellow port.
2. Make sure your computer's DHCP has been enabled.
3. Check your computer's IP address. For Windows XP, please go to Start-->Control Panel-->Network connections-->Local Area Connection-->Double click on it and then go to Support-->Details. Check what is the default Gateway. The gateway is the router's IP .
4. Then use this IP address to log into the TP-LINK settings page.

Have you put your username and password into TalkTalk modem and get Internet directly? If you did, then please select WAN-->Dynamic IP and go to LAN-->change the IP address to 192.168.2.1 and then save. This should work. If you need to dial up on your computer when you connect to talktalk modem, then select PPPOE and save. Hope you can get your router work now.

Thank you so much!!!It is working now. I followed your first instruction to change the LAN ip address and then it is working. Thank all of them.

I have problem with my router.
My house internet connect using dynamic IP.
Every time i using my router wifi (TL-WR740N) to get internet access from my modem , i need to clone my MAC address from my laptop. it works fine.
But if i shutdown everything and start again my router wifi cannot keep the information DNS address, IP address , all the configuration.
All address is 0.0.0.0 . because of this i cannot connect to internet.

What i do, to reset again the router and setting again by clone with my laptop Mac address.
Please help me to solve my problem with my router.

Thanks
Win