Files with the file extension 1ST are usually just text files. The extension is mainly used for so-called Readme.1st, so 'read me first' files. In this way, the user should be made aware of certain information that he should know before using the application or the data.
Since the extension 1ST is usually not linked to an application, it can not be started by double-clicking. The easiest way is to simply rename the extension to txt. 1ST files should normally be open with any text editor.
Most often resolving problems with opening 1ST files is very simple. Just install an appropriate program that supports such files. All of the listed programs support 1ST files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of 1ST 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 1ST 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 Notepad applications is not on the list, select "Browse" option in order to manually locate the directory where Notepad has been installed.
Sometimes problems with opening 1ST files may not lie with the application itself, but can arise due to other causes, such as: