Lightroom 5.7 not working after Mac 10.13 High Sierra installation

As far as I know, Adobe hasn't updated anything to work with High Sierra, It uses a completely new Disk format, which is why your photos are missing unless they are on an external?Me personally: I'm avoiding 10.13 for at least 6 months!

Sorry, but this is nonsense. Photos don't get missing because of the new disk format. They are still where they were, and Lightroom should still see them. I don't know about Lr 5.7, but Lr 6 certainly works on High Sierra and does see its images. Try resetting the preferences (hold the Shift-Option-Delete keys while starting Lightroom) to see if that works.

Here's what Victoria Bampton (Lightroom Queen) says about 10.13 (High Sierra) compatibility with older Lightroom versions: 
https://www.lightroomqueen.com/lightroom-macos-high-sierra-compatibility/

She's usually quite authoritative.  

It should be noted that LR5.7 is a legacy app and is no longer supported with updates.   The solution is to update to LR6.12.    LR6.12/CC2015.12 is not impacted by the update to High Sierra and indeed works as expected with MacOS 10.13 on my iMac..    Currently the new APFS is not compatible with the Apple fusion drives, only SSDs. And as such only Macs with an SSD are presently being converted to the new file system.  If your iMac like mine sports a fusion drive it still runs HFS+. 

I just upgraded a VM, as well as my MacBook Pro that I did a week or two back, before I wrote the post. The good news is 5.7.1 opened and worked as I described.

So we have to figure out why it's not working for you...

Error changing modules isn't an error we see often these days, but first port of call would be this tech note: https://helpx.adobe.com/lightroom/kb/error-changing-modules-lightroom.html

I just ran into the "Error changing modules" message out of nowhere last night with the latest version of Lightroom CC on my iMac running 10.13, but not the new disk format (everything is still HFS+). Trashing preferences has helped, but the startup catalog list still isn't retaining all of my catalogs.

So, I really need help. I recently had lightroom crash with 4317 of my working edited photos on it.  I panicked and brought it to a computer repair place to have them help me restore lightroom.  Two days later they called me to come get it, I came home, opened lightroom and every single photo is missing.  I COMPLETELY understand that the photos are not stored in lightroom (if one more person tries to explain this to me I will freak out). However, this is where I worked on the photos and the edits/changes I made to all these photos are stored in the lrcat.  Soooo, turns out the computer guys updated my Operating System to HIgh Sierra and now the photos are not longer in iphoto but in photos.  I cannot figure out for the life of me how to get them back into lightroom with the original edits.  I cannot even drag and drop them into lightroom like I used to, and when I try to export OR import, the photos category is grayed out and inaccessible.  Please someone help! I am a photographer and this is one years worth of work.