I have loaned a friend $23,000.00. I have a signed agreement but he has passed away last week. Is there anything I can do?

I'm sorry for your loss. Your friend's death does not extinguish his estate's obligation to abide by your agreement.  All valid debts must be paid before any bequests are distributed, and you can sue the estate to enforce the obligatin.  However, if your friend didn't leave enough money to pay you back, then you are out of luck.