and then when i come back, this is what it looks like:
The parts that disappeared are still there, but invisible. I can select the parts that are invisible, but they have no transparency. Its really strange. Please help.
If 1ik’s method didn’t work, then you might have to redo it. It happens a lot, and really, really sucks. If you want to stop this error from happening in the future, go to file, then studio settings, then physics and scroll down to disable CSGv2. That worked for me.