You deleted the wrong folders. If you want to “Clean” your solution you delete the Binaries, Intermediatte and sometimes the ‘Saved’ folder. You should never delete the “Config” folder - it contains all of your project-wide settings. It’s not the end of the world as they can be regenerated - but you will need to setup all of those project settings again.
Try doing it again from scratch, this time deleting the right folders. Also delete the hidden .vs folder and the solution file. Make sure the .uproject file is using the correct engine version too.
Did you change or upgrade the version of Visual Studio and are you working from a source build of the engine or the launcher version?