Character and compendium dropping

So, I was trying to drag and drop a mastiff because someone had bought one in my campaign and when I dragged and dropped i thought when it had asked fi you want this character sheet to contain the mastiff or whatever I thought it was only going to add it to inventory but instead it replaced the character with the mastiff character sheet and deleted the hours of play that their character had and they had multiple custom items that i had to manually add to their sheet. Is there a fix to this? or did I completely lose a character????? PLEASE HELP

There's a "Rollback Game" option in the games launch page settings that you could try. Not a bad idea to make a copy of your game (before doing it and in general) to have a little extra security. 

You might try to switch the toggle on the sheet from NPC back to PC.  Most (all?) of the info for the character should still be there.

Kraynik's solution should work for recovering the data. However, it would probably be a good idea to use this data to create a new character sheet. It's entirely possible some vital but unseen attributes may still remain overwritten with bad data.

Kraynic said: You might try to switch the toggle on the sheet from NPC back to PC.  Most (all?) of the info for the character should still be there. Where is the option for that?