The new update has plagued many of the devices with wi-fi issues. The most common issue is not being able to connect to the network after updating to iOS 7. This should fix all basic wi-fi connecting issue.
Fixing Wi-Fi Connection Issues
1. Settings > Airplane Mode > Turn On
2. Settings > General > Reset
3. Reset Network Settings
5. Restart the router and disable Airplane Mode. The device should now be able to connect to the network.