I booted up Lightroom today and now all of my libraries are now missing. It wouldn't be much trouble to add them again, but this means that all of my edits from the last 2 years are now gone too. Why would my libraries disappear and is there a way to get them back with the edits?
It sounds like you have opened a new catalog. Go to file and use the recent catalog item to open your catalogs until you find the correct one, alternatively search you hard drive for files ending in .lrcat. Is your catalog normally on an external drive which is not connected?