Solar Lights - DIY Quick Fix. Basically, there's a battery inside that charges the solar panel. Unscrew the head of the light and replace the battery. Will work unless the battery chamber has corroded.
The Original Starry Solar String Lights by Brightech – Warm White LED's on a Flexible Copper Wire – LED Light String Set with Solar Panel – Your Easy Way to Create "Instant Atmosphere" Anywhere. Recreate the Casual, Inviting Ambience of the Wine Count
This Solar Light Jack O’Lantern charges all day in the sun and turns on automatically each night to wow your neighbors and guests without you having to do a thing! Especially nice if you already have solar lights out front.