Open project, everything changed

So I open a project that I've finished (bounced), and most of the instruments are changed. They don't have their same effects. Example: a hand clap sound would just be a beep, or a synth lost all its setting and sounds nothing like the parameters I set, etc..) The structure of the sound is there, even the automation, but all the sounds are different. Why?

Very frustrated.

Thanks for input/help.