Cheap earbuds are disposable, but don't toss out an expensive pair. If the problem is a broken connection, you can fix them yourself with a soldering iron and electronics solder.
First locate the problem. If only one speaker is acting up, the problem is likely the connection in that earbud.
Use a small flatblade screwdriver to pry the earbud housing apart. You may have to superglue the two pieces back together when you're done. Look for a wire that's broken away from the circuit board. If you find one, first remove the blob of old solder with desoldering braid (from an electronics store) or an old piece of lamp cord (Photo 1). Then resolder the loose wire with.032-diameter electronics solder (Photo 2),
Allow the soldered connection to cool and then test the earbud. If the earbuds still don't work, you may have a broken wire at the jack. If so, resolder the broken wire.
If neither channel is working, the problem may be in the plug or jack. Replacement jacks are available online or at an electronics store for less than $5. Make sure you allow the solder to cool down before placing the bud in your ear.
1 DESOLDER FIRST
Wick up the old solder with desoldering braid for a fresh, clean start. Find it at an electronics store or online. Or use a scrap piece of lamp cord to soak up the solder.
2 SOLDER THE CONNECTION
Place the wire on the circuit board and hold it in place with the tip of the soldering iron. Add solder. Then remove the hot iron and hold the wire in place until the solder cools.
RELATED ARTICLE: Check the connections at the jack
Unscrew the plastic protective barrel and look for a broken wire. If you find one, resolder it.
COPPER WIRES TO LARGE OUTER TERMINAL
GREEN WIRE TO CENTRAL TERMINAL
RED WIRE TO REMAINING TERMINAL