Mefista, it's up to you to remember who you're in a transaction with and what items are involved. It's not fair to ask anyone who was considering selling you something to be the one to contact you like this--it's you who needs to keep better track in the first place. Do you keep any of your PMs?
If you're making transactions or inquiries when you're half asleep, it might be wise just to stay off the Trading Post during those times. Then you won't do something you can't remember later, preventing headaches for both yourself and the people who you're dealing with.
Also, moved this to Trader Support for you.