The value of double delta ct is provided in second last corner of attached excel . And fold change value in last. please explain how we can say that the gene is upregulated or downregulated .
In essence, you normalise expression for a treated and untreated sample by taking away the housekeeping Ct for that sample (Delta Ct)
You then subtract the untreated sample normalised (delta Ct value) from the treated delta Ct value (giving you a so called Delta Delta Ct value)
To calculate fold change in expression of your gene in a treated sample relative to the untreated control or calibrator you then use the delta delta Ct value as an exponent of 2; that is 2^ (Delta Ct Treated - Delta Ct control)
I have attached the original Livak paper and worked examples for you to adapt to your own situation