Sorry to hear, you're facing these problems. Would you mind to provide us the value of the following system registry key (by using regedit.exe)?
Computer\HKEY_CURRENT_USER\Software\Itoo Software\Forest Pack Lite\EffectsDir
Meanwhile, copying files from
C:\Users\<yourUsername>\AppData\Local\Itoo Software\Forest Pack Lite\effects
C:\Users\<yourUsername>\OneDrive\Documents\Forest Pack\effects (to User's Path) should help.
Thanks in advance for any further comments on this issue you can share with us.