Windows 7: No Internet Access on wireless network (TP Link)

I'm using DELL D620 laptop with Win 7 Ultimate OS, and I have trouble connecting to a wireless network, in fact I can connect to a network but I dont have internet access, I'm using TP-LINK (WR 741 ND (Annex B)) router.
Does anyone know how to fix this?
My boardband connection is working on a PC, and laptop, but I cant make wireless internet access on my laptop...
Please anybody Help me...

With this laptop, were you able to connect to the internet before using the same router?

What exactly do you mean when you say you can connect to the network?

This is kind of the problem I am having, the internet worked fine earlier today, now it just messed up I have tried everything

Dear Jumanji
My boardband connection is working on a PC, and laptop, but I cant make wireless internet access on my laptop...

Make sure that the wireless function on your laptop is enabled. (Check the User Manual on the how-to)

Other than that you have to configure your router correctly. Since I am not familar with this router, I cannot guide you any more than stating that there is a particular setting on your router under Wireless Setting to turn on/off the wireless radio function. Ensure that this is turned on and the front panel WLAN LED is flashing.

Go through the router manual and configure your modem correctly including the security settings.

If the wireless station is visible on your laptop, you can add it to the list in "Manage wireless netwoks". See the screenshots in the post No network shown in managed networks .

Sir, all setting is ok. now it working correctly but a problem is accured. due to electricity loadshading when modem and router are OFF and then ON then laptop connect to wirless network but it shows No Internet access (the same problem). Now.????