My files & folder has been hidden and also changed in .exe (dos mode) due to virus.how can I solve this problem.please specify all possibility then I recover my important data.thanks

Open with notepad. And save as *.(extension)

Changing the extension with notepad sounds like a simple solution but there are high chances you won't be able to use the file in this format, you first need to find a file extension that fits the requirements of the file so that you can use it for whatever you need. I learned this the hard way the first time I tried a new <a href="http://cloudsecurity.trendmicro.com/">cloud computing security</a> feature, now everything is under control otherwise I would have afforded to give you any advise.