you can go for PCR.

I personally tried out this method I mean the PCR, you just have to design specific primers targeting the whole gene

by PCR... of course.

That is indeed the beauty of PCR.

You can use the full genome as a template, but that's likely to not work due to secondary structure. Rather, it's best to either cut up the genome with a endonuclease that cuts on either side of your gene of question, or do a cDNA amplification by reverse transcribing the mRNA first. The latter will also remove the introns from your gene, letting you use it recombinantly in other organisms like bacteria.

Ya i also agree,,but what if pcr also does not work even if designed primers are very specific?

Another efficient way for gene isolation - is a recombinational cloning. This procedure can be used in RecA+ strains of E.coli or yeasts. The strategy looks like this 1) create a plasmid were you cloned 5' and 3' fragments (at least 20bp long in case of E.coli or 40bp in case of yeasts) corresponding to the ends of YFG (your favourite gene), it can be done using oligonucleotides; 2) treat the genome DNA with some rare cutting endonuclease that do not cut within YFG and linearized the plasmid to separate cloned 5' and 3' fragments (of course there must be appropriate unique site ); 3) transform the chosen microbial strain with both restriction mixes and wait for growing colonies on selective plate. To survive, microbe cell should repair the linearized plasmid by homologous recombination using YFG from the fragmented genome. This method is also refered as a gap cloning method.

Design gene Specific Primers by using nucleotide sequence of the gene..and perform PCR with the primers for further confirmation of gene perform RFLP or do sequencing of the gene and with the obtained sequence perofm BlastN against database...

PCR with gene specific primer