Left fuel valve in "prime" position overnight!

[JerseyMitch]

Okay, so I didn't know any better and left my bike's fuel valve in prime position overnight for, like, 12 hours. It has a new battery and new plugs (just put them on today.) As soon as I realized what I'd done I changed it to the proper position (as per the manual.) But the bike won't start.

How bad have I screwed up? How do I fix this so I can actually ride this bike?

A little background info: It's a 2004; I bought it for $1,100 from a guy I know. He told me it would need a new battery. It worked great yesterday, the first day I rode it. Since I'm a new rider I rode with some more experienced friends. One of them fiddled with the engine for me, making the fuel mixture a little richer. We filled it with mid-grade fuel, not premium. And left the fuel valve in PRI position overnight.

Today it started, but then quickly stalled out. I replaced the battery & plugs. All this time the fuel valve was in PRI. This evening I looked at the owner's manual (better late than never) and saw the warning about the fuel valve positions. I changed the position to ON, but now the bike won't kick over.