I have had LR5 which I installed as an update from LR4, through adobe, some 6 months ago and, until now, have had no problems. Yesterday I tried to open Lightroom and could not, it just briefly cycled then nothing. I have trie several times but cannot open LR5 on my PC. I have changed nothing, no settings, programs...........nothing. How do I open LR5 ?
Please try below steps
Backup your catalog first.Go to Pictures/Lightroom and copy catalog to Desktop
Navigate to C:\Users\USERNAME\AppData\Roaming\Adobe\Lightroom\Preferences
(**Appdata is an hidden Folder(Refer Show hidden files - Windows Help) to show the hidden folder)
and rename Lightroom 5 Preferences.agprefs to Lightroom 5 Preferences.agprefs.OLD
Let us know if that helps