No, you can't re-create a SCH file from the PCB files you have already generated based on the SCH. Those SCH files are used to generate the PCB files, but the process is not reversible. However, try opening a PCB file, then recreate the SCH manually, based on a visual guide, because this is the only way possible to have the SCH files back on your computer. Alternatively, check the built-in HELP file to find additional information about this procedure.
