Those are common "Christmas Tree" lights. You said there are 10 per stake, so get ye to the Christmas Store and look for replacement bulbs for a 10 light string.
The "Star" pulls off the light, you can either repe teh entire lamp assemble (lamp and base) or you can replace just the lamp (Lamp with wire leads, you remove the old bulb and insert the new one)
Like the standard Tree string only one bulb need to be bad, The Christmas store sells a few different "Bulb Checkers" that will help you find the bad one.
or you can just replace all 10.