I just spoke with support regarding this exact same issue. The end fix was to do the following:
- Close origin
- In C:\program files (x86)\origin games\ move the whole titanfall folder to a temporary location, eg : c:\temp\titanfall
- Launch origin, titanfall should say download
- Close origin
- Move the titanfall folder from it's temporary location back into \origin games\
- launch origin again
- BAM! titanfall is now able to be played again.
