Which version of FMP are you using?
The Update FMP 12.0.5 is dedicated to meet Mavericks requirement. If you're on a older version, I'ld highly recommend to perform Update 12.0.5 and try again.
Next step would be to uninstall all FMP resources and reinstall from scratch.
Thank you for your post.
I just talked with our Customer Assistance department, and they are emailing your original FileMaker Pro 12 download link. You can then download and reinstall FileMaker Pro 12.
If you do not receive the download link within one hour, please let me know, and I'll make sure the link is sent to you immediately.