My minecraft mods messed up?

I use minecraft modinstaller, and i have doggy talents, twilight forest, mo creatures, and orespawn. I have had these mods for months now, and have had no problems until today. Every one in a while, i try out another mod, and i did today. When i downloaded it and went to minecraft, all of the mods were uninstalled. I got out of minecraft and went back in, and all of the mods were back, but there were mob spawners and generated buildings everywhere, and all of the modded blocks were changed to different ones. There's no way somebody could have come into my world that fast and tried to troll me or anything, so i think teh coding must have messed up. Please Help! I HAVE BEEN WORKING ON THIS WORLD FOR 4 MONTHS!

Sounds like you've added mods that has ra random structure generations and also uses the same IDs as blocks that were in your other mods which is why blocks have changed. Unless you made a backup of the world before the change, there isn't anything you can do about it. I always make a backup before changing any mods I have installed, I also have test world which is the first world I load to see if anything dodgy has happened.

Ahhahahahahha lol thats what you get for not using a real modpack or a build your on on other launchers… You signed in on a non modded profile (most likely on accident) and then went to continue the world. Your computer had only 2 choices convert all unknown blocks or crash the game… You know which was chosen and unless you have a previous save thennn you can't get it back lol again just use at launcher vanilla and you can install your own mods and it will keep them separate for you