I was actually asking because I invested a tiny amount into the Let It Ride ICo from last year or whenever, but saw that it was still being traded on YoBit, I believe. But I never transferred my coins out from there to another exchange, kind of forgot about them actually so that's what I'm meaning by dead, the coins may still exist so long as there are people trading it, but since I left mine in there, I can assume they are dead and buried with no option to recover them?
Only if someone is willing to buy them will you be able to sell them. There are people who look to buy dead coins, but it's very far and few in between and it's never a good idea to try to do that.