My Internet works fine on my computer but does not work on my iPhone (4s)?

Now I've had my iPhone for over a year now and has always been able to connect to Wi-Fi in my home. Nothing has changed at all and I have not physically damaged my phone. When I go into settings on my iPhone, it does not even show my network that I should be automatically connected to at all. On my computer the internet works just fine. Is there any way I can fix this issue?

Added (1). I have already tried turning my phone on and off, turning on airplane mode on and off. I have also tried to reset network settings

Goto settings, general, reset, and click the "Reset Network Settings"

Reset the router and uninstall a bunch of useless apps on your phone that r consuming data in the background.

Try the following.
1.) First of all, switch off the phone and again turn it on (restart). This should normally fix the issue.
2.) Now, search for your network. If it is not found, check whether the device recognizes other networks.
3.) If it recognizes other networks and connects well, it it the problem of your Wi-Fi router!
4.) If it doesn't recognizes other networks, you may have to contact the Apple Customer Care.

Firstly try too use 3g service. If your network works fine so check your connectivity issue. If its not works well so Your Gadget have not a strong network.