Did your sims travel, move out or were evicted recently ? If yes, the sim associated to the IF has been lost and you should revert to an older backup.
If you want to see if the sim associated to the doll still exists, use MasterController to check the whole population and see if you have a sim named Jasper in your list. If the sim is there, you can use DebugEnabler to (re)set the doll's owner. DebugEnabler won't do anything automatically, all it can do with IFs is setting the doll's owner. If Jasper isn't in your town's population, I'm afraid it's been lost and nothing can be done other than reverting to an older backup.