Read ADC sine wave values

In addition to AWOL's comments -

With these variable definitions:

float VCO;
floatVCO_Final2[10];
float VCO_Final;

your code below does not compile.

for(i=0;i<10;i++)
   VCO_Final2= (5.0*VCO)/1023.0; //Read VCO and store in an array
 
 VCO_Final = VCO_Final2; //take every element of array into another single variable

When reading the comment, the question "why?" remains ...
Is there something with the scope of your [i][b]for( ; ; ) {  }[/b][/i] range, which you intend different than you do ?
What's the purpose of that array ?

What's the reason to include code that is not used ( Cable_fault, calculate )
Trim posted code to the minimum showing your problem, please.

Edit : take care not to have smileys in code