Isopropanol is more susceptible to salt carry-over.  You could try more ethanol washes and possibly at higher temperature (0-4deg... on wet ice for 30min should be enough). How sure are you of your isopropanol and ethanol concentrations - were they measured accurately?

There are few good guides on bitesize bio about this basic stuff.

http://bitesizebio.com/253/the-basics-how-ethanol-precipitation-of-dna-and-rna-works/

http://bitesizebio.com/13513/how-to-get-a-perfect-pellet-after-dnarna-precipitation/

http://bitesizebio.com/2839/dna-precipitation-ethanol-vs-isopropanol/

And another extensive one from Cornell.

http://physiology.med.cornell.edu/faculty/mason/lab/zumbo/files/ETHANOL_PRECIPITATION.pdf

Effect of temperature on this process

http://biology.stackexchange.com/questions/15236/isopropanol-precipitation-of-dna-duration-and-magnitude-of-cold-storage

An interesting aside (perhaps not so applicable in this instance as the solvents are v/v and so easily measured), solvents diluted in another liquid often display some interesting properties i.e. be careful when presented with conversions between molarity (essentally w/v) and dilution percentages (often v/v).

http://www.bode-science-center.com/center/hand-hygiene/hand-disinfection/detail-hand-disinfection/article/ethanol-concentration-table-what-is-the-percentage-by-volume-or-weight.html

Thanks a lot Pete Gee. I will try.

 Thanks a lot  Dr. David. So is there any way to rescue my DNA? Should i repeat chloroform/isoamly alcohol step?

Thank you!!!!

Thanks a lot Dr. David for suggestions.

Here are the references for David's comments.

Marmur:

http://www.sciencedirect.com/science/article/pii/S0022283661800478

And subsequent interesting commentary:

http://garfield.library.upenn.edu/classics1991/A1991GB94800002.pdf

And here is another modified procedure referencing the original method and a modified version, as well as outlining another one:

http://www.sciencedirect.com/science/article/pii/0003269787900054?via%3Dihub

As can be seen in table 2 of the later Mamur's original protocol results in significant protein contamination (~43%).  Additionally, it takes much time and optimally requires 6g w/w of bacterial pellet.  There are now numerous protocols that are much quicker and easier at isolating high quality genomic DNA.

Our lab regularly deals with archaea that are recalcitrant from complex (contaminating) environmental and fecal samples.  We regularly use a modified CTAB method outlined below in conjunction with additional clean-up steps (sometimes using commercial purification columns) as required.

http://www.biotechniques.com/multimedia/archive/00036/BTN_A_04365ST04_O_36541a.pdf

A couple of good reviews of a number of different methods can be found here:

http://onlinelibrary.wiley.com/doi/10.1111/1755-0998.12620/epdf

http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0074787&type=printable

It really depends on your source and downstream application as to how much and how pure you need it. There is invariably always a trade-off between sufficient nucleic acid purity and yield.  Each is important and should be carefully considered, as there can be ramifications in the validity of conclusions you can draw from results e.g. with quantitative RT-PCR sometimes yield is required for sensitivity as long as low purity does not inhibit the PCR reaction efficiency in itself; another example is having a robust lysis procedure when surveying complex samples in microbial ecology analysis - if you're not lysing ALL populations of cells then you're immediately biasing your results!

Cost is often also a consideration (and remember not just in terms of kits and reagents - time and labour cost is often the largest driver of total expense!). If you're just looking to get template for transformation or standard PCR then you should not have much trouble and I'd go with whatever is easiest (e.g. a miniprep kit) but if you've got hundreds or thousands of samples and are doing other 'things' with your DNA then significant thought and some time spent optimising your procedures is definitely worthwhile.

Thank you for the suggestion Dr Peter.