Thank you. Glad that you like the new forum
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The source file is never stored in the PLC. Only the compiled codes and the name of the original source file are transfered to the PLC. So when you format the PC harddisk, the source files are lost.
The "Open matching file" function will ask the PLC for file name and attempt to locate the same file name in the source folder of the user who has log-in. Since the source file is already gone that's why you receive an error message.
Likewise, when you open a file from the TLServer, the TLServer open the files from the PC hard disk, not from the PLC. Again since your source file is already lost when you reformatted the PC, it is not there anymore.
I guess if you don't have a backup you will have to key them in using the hard copy. Test it using the simulator before you transfer it to the PLC. Alternatively, you could purchase a spare unit of the PLC to play with so that you will not affect the original working program.