1) See if you can connect using a Linux Live disk.
If you can connect, you know the problem is with your OS and not a problem with hardware, router, etc. NOTE: Make sure that your WNIC is supported by Linux and the distro (including any firmware).
2) Reinstall the wireless device with no other network devices installed.
Uninstall all network devices and physically remove them from the PC. If you have onboard NIC, disable in BIOS. Make sure NIC's are gone from Device Manager. Then, reinstall the device following the TrendNet's directions.
3) Factory reset and reconfigure the router. Follow the directions for your router model.
These might help you in troubleshooting your problem.