It’s from Stardew Valley. The only translation I’ve been able to come up with is from Google Translate >.< Even my Japanese teacher didn’t quite understand and couldn’t explain it. I understand that “この手紙を持っていて” means “to have this letter (-te form)” but I cannot figure out where “これないか” comes from or how it relates to the sentence.
~てくれる is used to talk about a favor done for the speaker by the listener. If you search you’ll find lots of info on it. So using the negative form like that poses it as a request for a favor to be done.
Literally くれる just means “to give (from listener to speaker)” but it can be appended to the て form to function as an auxiliary to mean “please do this verb for me.”
The humble version of くれる is くださる, whose command form ください, you’re surely quite familiar with.
In that negative form for くださる you might see 持っていてくださいませんか
It’s definitely 持っていて. “Won’t you hold this letter for me?” does make sense in context. The game shows your grandfather holding a letter and it jumps towards you. It makes sense in a video game kind of way.
Yeah, I guess it means “please keep this” in that sense.
EDIT: The “for me” would not necessarily be said in English, as that implies something maybe more specific than the Japanese does. In Japanese it just means that the speaker is getting some kind of benefit from the listener doing the action, where as “hold this for me” in English would probably mean the person just needs you to grasp it for a moment while they go to the bathroom or something.