# How can I get the second derivative and the reciprocal from the result of NDSolve?

I have obtained a result h(x) from NDSolve data. I can plot it

data = Import["C:\\Users\\...\\Desktop\\data.dat"];
ListLinePlot@data


Now I want to get the 2-nd order derivative of h(x) with respect to x, i.e. hxx, and the reverse of h(x), i.e. h^-1, in order to proceeding other calculation, such as, to plot the function of h^-2-hxx. Anyone can give me some guides or advice on this issue? Thank you very much!

Let's pretend this is your data

dat = Table[{x, 2 Sin[x]^2 + Cos[2 x]^2}, {x, 0, 2 \[Pi], 2 \[Pi]/100}]


Ok, not your data, but similar enough

ListPlot@dat


we create an Interpolation function

 f = Interpolation[dat]


and then just calculate derivatives and inverse

Plot[
{
f[x]
, f''[x]
, 1/f[x]
}
, {x, 0, 2 \[Pi]}
]