If it’s only a single file, and if you’re using Tortoise SVN, you can use the following approach:
1.Right click on your source file, and select “TortoiseSVN” -> “Show log”.
2.In the bottom window that show changed files, right click on a file, and select “Save revision to…”.
3.Let the saved file overwrite your current file.
4.Commit the overwritten source file.