Fix solar garden lamp?

I have a couple of garden lamps that should be solar powered, but after a few years, they do not work. Is there a way to fix them? Can I make my own?

Most ive seen are powered by cheep rechargeable batteries. Open one and see if its something standard like a AA and the just go and buy you some rechargeable batteries.
... and choose NiCad instead of NiMH, because even though NiCad are lower capacity per cell size, they withstand more charge cycles, perform better when it is cold. Just make sure you properly dispose (recycle) any battery chosen including the worn out original cells. If you have a multimeter, it might be good to go ahead and check the diode, assuming there is one between the solar cell and the battery pack, just to rule out it being the failure point. It is not common for it to fail in a low current design like this, but better to know it is ok before buying the batteries, and the same goes for checking that the solar cell is producing power with the voltage range on the multimeter, and that the wiring and solder joints or splices are ok with the multimeter continuity or resistance check.