Changing a negative feedback

A user left me an negative.I will just reship his item.
After 20-30 days can he still change his negative? or it's possible only for few days/?

Dude, I think you should give up on Ebay. This is the third thread you opened like this.

http://www.blackhatworld.com/blackhat-seo/ebay/577540-i-refunded-buyer.html
http://www.blackhatworld.com/blackhat-seo/ebay/571603-negative-feedback-left-axxhole.html

hahaha, how many threads do you need in order to ask the same question?

you're going to have to send the buyer a "revise feedback request." they have to then agree to revise the negative feedback that they left. 99% of the time they will not change it even if they promised to.

you can only submit one feedback revision per negative feedback and they are only good for about a week. so if the buyer doesn't change their negative feedback within a week then you will not be able to send another feedback revision request.

You worry too much about this stuff! There will always be times when the buyer is a jackass and you can't waste this much time and energy worrying about every single negative review you receive.
100% positive feedback is impossible just make sure you're above 4.6/5 and everything is fine!