Hi obarriel,
that could be a tricky job as LV2013 claims "block diagram can't be opened"!
Meanwhile you should learn two things:
- using LLBs isn't recommend practice nowadays (atleast not for storing daily work VIs)
- make a backup of your works on a regular basis (using SVN/GIT is recommended too…)
Best regards,
GerdW

using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019