my wifi keeps turning on and off how do i fix this ?

Either your wireless router is failing or there is a source of Wi-Fi interference present that is causing your wireless router's signal to be unstable.

Assuming that the router is not faulty, I would suggest you perform a simple site survey, using utilities like iStumbler, or AirRadar to determine potential areas of interference, and then, try to either eliminate or significantly reduce them where possible.