WiFi suddenly inaccessible

Hi.

At 7.00 AM this morning my iPhone 5 suddenly decided on its own accord not to access my home WiFi.

I checked a second iPhone 5 in the house and it was fine.

I compared settings and they were both exactly the same (with different DHCP IP address of course).

I turned off WiFi and iPhone could access Internet through provider 3G account OK so switched WiFi back on and set up once again but still refuses to access my home WiFi.

I use Apple Time Capsule. Green light showing.

I see others on this Forum have similar WiFi problems.

Any ideas for a solution please?

Michael