from some how, I read to erase all old meeting data, so I need to recover
all of stuff I deleted. May I get help with that?
Sorry you're stuck but there's almost always a pretty easy fix! Do NOT try to start all over again, eg. uninstall Max's Pitch Package, etc. That can make things worse.
Before you post make sure you check the Help FAQ for an instant solution first. Then, if you can't find it there, you can post your problem here and we'll get to it ASAP (within 24 hours), but be sure you:
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Well, you can always recover any record that you delete by going to the App Launcher and entering "Recyc" in the search box so you can find & open the Recycle Bin app. Then when you open it, it will show all the records you deleted and you can choose which ones you want to recover.
But in your case, I see way too many Meeting records already. It looks like you imported the file twice. And it also looks like the numbers are slightly wrong because you deleted one before you imported, maybe?
So now it is kind of messed up and you may have to delete your whole Meeting object and redo the last part of 2a, starting where you create the Meeting object (and all the Meeting records inside it), and going on from there to the end of 2a so then you can do 2b properly.
Let me know if you need help with that.