How to join file?

1. Some files have "rar" extension for which you require "WinRAR" to extract the movie.
2. Some files have ".001" extension for which you require "HJSplit" to extract the movie.
3. 3. Some files have "._a" extension for which you either require "FFJS" to extract or else rename the extensions to ".001, .002, .003...." respectively and use HJSplit.
4. Some files have ".a00, .a01, .a02,..., .alz" extension, for which you have to download "ALZip" for extracting the movie.
5. Some files have ".vnw" extension in the end. For such files, create a back-up in some other folder. Now rename one set of files to ".rar" and use "WinRAR".