It depends when you encounter the problem, You cannot plot complex data, so a + I *b need to be transformed to {a,b} before calling to ListPlot. You can do that using ReplaceAll

so

tab=RandomComplex[{-0.01 - 0.01 I, 0.01 + 0.02 I}/10000, 100]; ListPlot[tab /. Complex[x, y] :> List[x, y]]

If your problem appears AFTER importing back the data, you need to notice that the data is imported as strings and you need to use ToExpression to overcome that

exp = Export["~/table.txt", tab, "Table"];

imp=Import[["~/table.txt", "Table"];

Dimensions[tab] returns 100

Dimensions[imp] returns {100,1} so there is a surrounding List that you can cancel using Flatten

so for this part

ListPlot[Flatten[(ToExpression@Import["~/table.txt", "Table"])] /. Complex[x, y] :> {x, y}]

will do the trick HTH yehuda