hard copy game help for pokemon gold

i was playing it the other day on my gameboy color when i turned it off a few hours later i went back to keep playing and my save was gone. anyone have this problem?

 

your internal battery is dieing n he game so it wont keep your saves anymore

 

@_@ it dies =o how do i recharge the battery =o

 

You can't, I think

 

o___o so i cant like take it to a store an they fix it?

 

Actually, you can try to replace the battery yourself, here's a pretty good step-by-step with pictures.
Haven't tried it myself as I don't have any old carts but apparently it can fix your saving problem if done correctly.