More than 10 days ago, I restored my system in safe mode to a certain restore point becuase windows explorer was not responding. After system restore was completed, I lost a folder (named Data), and all the files it contained, which I created in C:\Windows.
Why would system restore do that?
And is there a way to retrieve my files??
Never put a file you want later in the Windows folder... always store it in your User folder. I'm not absolutely sure of this, but I imagine what happened is System Restore found a folder in C:\Windows that wasn't there before the last restore point. System Restore most likely removed the folder because it didn't think it should be there.
If your files are lost, it's more likely that some program deleted those files. One way to recover them will be using data recovery tool, you may follow this guide http://goo.gl/Z85jj
It could be virus or malware which deleted your files. So it will be better if you can scan your computer hard drive with anti-virus software. Recommended Microsoft Security essential which you can download from http://goo.gl/rx1KFq