Text keeps turning gibberish

Hello, something weird has happened to my templates. When I preview them It looks like this, but when I change font it's fixing the problem then I can get back to helvetica and it works, any fix? It can’t be corrupted font, it’s just helvetica and it used to work.. like a month ago. 

This seems like it could be a font or font cache corruption issue.Here are some suggested actions to try (quit FCP first, if it's running):

• - Use Font Book's Resolve Duplicates and Validate Font functions to determine if there is a problematic font, then remove it.

• - Restart your Mac in "Safe Mode" (to clear font caches):
•  Start up your Mac in safe mode - Apple Support 
• After starting in Safe Mode and logging into your account, restart normally.

Let us know how this works out. Thanks.

Did everything what you said, but I opened FCPX during the "safe mode" and It works, font appeared as a normal and working, but back... to "normal mode" I checked and there is still this problem, but in SAFE MODE they were working just fine. Any ideas what can I try yet? Thanks in advanced.


UPDATE: I restored all of DEFAULT font in FontBOOK and unistalled third-ones, and it seems to be working now. 

Cool. I was going to have you do "Restore Standard Fonts..." next. It seems like the actual Helvetica font got corrupted.

Glad you got things sorted...