Snapring coming loose

[RxHeadKicks]

I've just bought this bike, 26" schwinn drifter fixed gear, and every time I get on it to go out, the retainer ring pops out and the sprocket comes loose, pedaling does nothing, and brakes do nothing. Every time I pop it back in it comes out. How do I keep the snap ring from popping out?

[JohnV]

Which sprocket? Is it the rear cog or the front chainring? A better description and a photo will help solve the problem much faster.

[DaveM]

I've seen this issue before - cheapo snap ring. You need to get a new snap ring, hopefully one made of a bit thicker gauge wire. (But it still has to fit into the groove on the hub.) On the two I've seen, the metal of the snap ring is just too thin to hold the cog firmly, so it wobbles a bit and pops the ring off.
Try a good bike shop or hardware store, bring at least the old snap ring for comparison.

Note that you don't have a "fixed gear". You have a "coaster brake" single speed. Just so you use the right terms.