I turn on the wifi of my iphone 4s but it dont show any wifi signal around me

From apple:

1 Make sure that your router is on and you're within range

If you're too far from your router, you can't get a signal, so make sure that you're within range.

2 Make sure that Wi-Fi is on and you can see your network

Tap Settings > Wi-Fi and make sure that Wi-Fi is on. Tap the name of your Wi-Fi network to join. A blue checkmark beside a network name means that you're connected. Get help if you can't turn on Wi-Fi.

3 If asked, enter your Wi-Fi password

If asked, enter the password for your Wi-Fi network. Get help if you don’t know your password.

Even if you enter the correct password, you might see an "unable to join the network" message or an "incorrect password" message. Restart all of your devices, then try to enter your password again.

4 Check for issues with your Wi-Fi network

If iOS detects an issue with your Wi-Fi connection, you might see a Wi-Fi recommendation under the name of the Wi-Fi network that you're connected to. For example, you might see the alert "No Internet Connection." To get more information, tap the Wi-Fi network.

5 Check your cables and connections

If you still can’t connect to your network or get online, make sure that your router is connected to the modem and turned on.

Restart

Try restarting your iOS device, router, and cable or DSL modem. To restart your router or modem, unplug it, then plug it back in.

After you restart each device, see if you fixed the issue.

Still can’t connect?

Reset your Network Settings. Tap Settings > General > Reset > Reset Network Settings. This also resets Wi-Fi networks and passwords, cellular settings, and VPN and APN settings that you’ve used before.

Get more help

• If someone else set up your network, ask them for help. If you’re using a network at a company, school, hotel, store, or other free Wi-Fi location, find an employee for assistance.
• If you're connected to a Wi-Fi network but you can’t get online, try to use your Wi-Fi network on other devices. If you can’t get online using your other devices, there might be a service outage. Call your cable company or internet provider for help.
• Try connecting to a Wi-Fi network in a different location. If your device can connect, you need to get help with your Wi-Fi network. If your device can’t connect to any Wi-Fi networks, contact Apple.
• Update your Wi-Fi router with the latest firmware and make sure that the router supports your Apple product. For more information, contact the router's manufacturer.