Lost all color grading on a 2021 project!

Using Resolve 19. When I open I see a list of all my projects from the beginning about 5 years ago. I had to make some changes to a project from 2021. To my horror I found that the color pages have no settings. All the work I had done to about 3 hours of content seems to have disappeared. Does anyone know why this would happen? ....and is there a way to get the Color Corrections back?

I don't know what to tell you except that -- especially for a 3-hour project -- I'd have a half-dozen DRP backups for something like that. I try to date them for every day I'm working (say, Project_v1_5-5-2025, Project_v1_5-6-2025, Project_v1_5-7-2025, Project_v1_5-8-2025) and so on, and then finally wind up with "Project_Final_Color_5-10-2025.drp" (or something like that). Worst case, I'd always have some of the preliminary sessions, so I'd never have to completely start over from scratch.

I also grab Gallery stills for every shot in the entire show, with final color, and export the Gallery stills (with the associated DRX grade file) to a separate backup folder. We keep that, plus all the associated XMLs for the timelines, and nowadays, DRT timeline files as well. And we export Media Managed copies of the whole session to archive drives. We do all this as a way of protecting ourselves (even in the event of nuclear attack).

Losing all the grades is not impossible, but it would imply a couple of possibilities:

1) somebody got into the file when you weren't looking and zeroed-out all of the color in the entire project

2) you thought you were saving a final project, but in fact were saving a preliminary project that had yet to be graded

3) the project is profoundly corrupted to the point where all the stills and color have been lost.

Usually in the case of #3, the project also won't open up, and the reality is that's pretty rare (but it does happen, like in the case of a drive running out of space).

Check to make sure you haven't hidden or deleted alternate timelines. Once in a great while, I jump back into a project and realize I'm not working on the "final" timeline, so I have to quickly switch over to the real one and continue the work. It's only happened a few times, but at least now we have the ability to "hide" timelines to avoid confusion. I also rename those timelines with the word OLD as a prefix, so there's no possible way I'll open it up by mistake. Versioning is another possiblity: V1, V2, V3, and so on, and just make sure you use the latest version.

Thank you for that amazingly detailed response! I'll have to investigate what "Gallery Still" means exactly. DR is deeply complex (to me) and I've coasting on a few basics for years. I have to confess that my initial assessment of the timeline was not entirely correct. When I first opened the timeline yesterday I was looking at a section that seemed dark to me, so looked at the color page saw everything zeroed out, like the settings were never touched. And I did some spot checking So I assumed I had lost all my color corrections. Today, I looked through other parts of this very large timeline and it looked "not so bad". I found my output files made that the time and those closely matched the timeline (though slightly lighter). So actually it seems like it's OK. Nonetheless there are no color grade settings visible. So... somehow the scenes still have the adjustments, though I can't see any settings on the color page. And yes I do know for sure that I did color correct as it is documentary footage and exposures were all over the place. In any case your response was valuable and I'm creating external backups of projects from now on. Thanks so much.

Long shot but some things you could check:

First that you are looking at the grades at the Clip Level rather than Timeline Level. Do this in Color page at the top of the node window, it either says Clip or Timeline. The Timeline one affects all clips in the Timeline rather than each clip.

Also maybe you have accidentally started a new grade version? Color Menu -> Grade Version

Also in the Color Page Media pool, right click on one of the Clip Thumbnails, you can see if you have additional versions in the pop-up window (you'll see Version 1, 2 etc). While there make sure you are seeing the correct version of Local Version vs Remote. Each of these can have more than one version. Multiple versions is usually for comparing different grades.

also, look at the remote vs local grading, you might have switch that setting.

ALWAYS duplicate the project before attempting anything....

To start (as many have already stated before me):
Definitely duplicate the project first before you open it, do any changes, whatever.

It reminds me of the time I had lost an entire timeline for obscure reasons about 3 years ago. Luckily it was just a 2 minute trailer and it was before the color grade, so I just lost like 2 hours of conform work that could easily be recreated. However what I found to be the "reason" for the loss was a bug when the render cache location was missing and the project itself was relatively big.

So what you can try it to open the project in read-only, look at what the error message (missing render cache location) says. manually recreate this missing path in the finder/explorer, so Resolve finds it automatically. Reopen the project in read-only again and pray that it helped.

Apart from that I can't think of anything that hasn't been suggested before.