If it's something related to the hardware, try visiting the
Wii Support website, either reading their help topics or contacting them directly. That way you can find out if it's something you can fix yourself or if it will need to be repaired/replaced.
One thing that has happened to me several times is that it will not turn on at all. This is because my power company is
horrible. It'll be a bright sunny day and the power will flicker off and back on as if it's gotten sleepy and nodded off. -_-' Anyway, if that every happens, what you have to do is unplug the power supply from the back of the Wii
and from the power outlet (for good measure, I unplug everything.) Leave it off for at least two minutes. Then plug it back in and everything has reset, I guess. In any case, it fixes that particular problem.