I updated my mods today to the latest update and since then it just doesn't load this mod properly. I've tried all the basics like reinstalling the mod, trying a different version and every time it either crashes or says it has failed to load correctly.

exception message: java.lang.NoSuchMethodException: brentmaas.buildguide.forge.BuildGuideForge.()

I can see that you're using Forge 1.20.4, but I can't reproduce this using either the development version or the production versions. Could you provide a bit more information and/or upload a (crash) log?

I have a pretty good idea what this might be. I think the version of Forge you've used doesn't support the constructor I've written (BuildGuideForge(FMLJavaModLoadingContext)) and would rather use a default constructor (BuildGuideForge()). However, this doesn't appear to occur with the latest version of Minecraft Forge for 1.20.4 and today's release of Build Guide, so I'll close this issue for now. If you still have this issue on these latest releases, feel free to reopen.