Is it possible to amplify AC signal with In Amp in Single Supply?
I believe that a in amp with a single supply, for example 5V and GND,
  can not amplify negative signals because the power is not symmetrical.
  Right? Or not?


Correct, this won't work. The full range of the input has to be bounded within the power rails of the InAmp. In fact it's a little tighter than this if you look at the data sheet.

If you look on page 5 it tells you the "linear input voltage range" and this is restricted to typically -Vs + 0.95 volts and +Vs - 0.65 volts. In your situation, with a 0V and 5V rail, the input range is +0.95 volts to +4.35 volts. No amount of fiddling with the ref pin is going to alter this.

There are similar restrictions to the output voltage range too.