The extension WBK features auto-backup files from Microsoft Word documents. The extension is used in the versions starting from 2007 (Mac 2008) of Word. Later versions use the suffix asd. The files can be used to recover a document after an error.
WBK files are created automatically if the option 'Always create a backup copy' is selected in the settings. These can be found in Word 2007 under Word Options-> Advanced.
Most often resolving problems with opening WBK files is very simple. Just install an appropriate program that supports such files. All of the listed programs support WBK files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of WBK files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate WBK files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the Microsoft Word applications is not on the list, select "Browse" option in order to manually locate the directory where Microsoft Word has been installed.
Sometimes problems with opening WBK files may not lie with the application itself, but can arise due to other causes, such as: