Put all your clean and repaired parts back together, along with the partially recharged batteries. (You can try to fill in the gaps with something if you want to prevent bugs from getting in).
Then Stick your finger over the Light Dependent resistor (usually next to the solar panel) and turn it on. Does the LED light up? Hooray! :) Congratulations on fixing your old light. Now just stick it back in your garden and enjoy it's glowy goodness.
If it doesn't work, you better go back to step 1... :(
Watch this space for more tutorials from Rhodesy.
You're on the Rhodesy to success with me!