You selected "Fastcut" as your Magix product but then ask about "MEP v17". Can we first establish exactly which product you have?
Then, can you post a screenshot of the error message, or at least the full wording?
It sounds very much as if your installation files have been somehow corrupted and that a complete uninstall and reinstall may be needed. You could try a Repair Install (just run the original installer file and select the option to Repair) but this is not guaranteed to effect any change. In that situation you will need to completely uninstall and then reinstall the software.
This uninstall/reinstall procedure must be carried out correctly. Post back if you want more details of how to achieve this.
THANKS FOR YOUR POST - I did as suggested looked for the installation file (missing) and decided that I would upgrade to MAGIX Movie Edit Pro Plus 21 as this seemed the most cost/time/effective solution. All done!