Can somebody help me solve r" = -C/(r^4) where c is a constant, and r" is the 2nd order dervative of r (wrt time)

We tend to steer clear of homework questions here, if that’s what it is.

I do not know much about solving differential equations, but I can recognize one when I see one, and that is what you have. It is not just a simple matter of differentiating or integrating. The equation you have is:
x’’(t) = -k/x^2
The negative sign is needed if the magnets are attracting each other to account for the fact that the force is in the opposite direction of increasing distance.
Gravitational attraction follows the same type of inverse square law. You should be able to find something on this in a textbook on physics or differential equations.

Yeah Ive downloaded a couple of Diff eqn examples and googlebook excerpts but there isn’t any step by step method of solving. plenty of examples which resemble this (the eqn form).

jmah thanks for the concern, this isnt homework though. Unfortunately Im too old for that now =P