No! Your game is not screwed so calm down.
Quite simply - there is a watch battery inside it, and it has
ran dry, so it cant hold your save file anymore.
There is no 'internal disk', the insides of a GBC cart are a
green circuit bord and romset chips, as well as a clock controller in this case and a save chip which is powered by the battery that has failed on you.
This is a known issue, and the thing that annoys many players
of this game is that Nintendo will not deal with any such replacement of battery, as the games are 'old'.
this is from a forum topic in the pokemon silver section of GAMEFAQS.COM - written by Uriel3ca3 - not by me
Why won't my game save?
Why isn't my game clock keeping time correctly?
Problems like this are common lately for people who have played a lot, because these games use their internal batteries to save data. Like any other battery, they run out of power over time. Eventually, you won't be able to save your game anymore. Unfortunately, your only options are to buy a new copy or get the battery replaced. Try taking your game to a local electronics store to see if they will replace the battery for you, but be aware that any saved data you do have will be lost when you do this. You could also try replacing the internal battery by yourself, but it is not recommended.
If you are adventurous enough to try and replace your battery, then please follow this handy little guide. Be warned though, neither gamefaqs, myself or the guide's author are responsible for any injury or damage done to you or the game pack. Intro
Ok! So Im writing this on Gamefaqs' message boards so Im sure there are some formatting errors in here. My pokemon game stopped saving so I checked the forums here and found a great guide that tells you how to replace the in-cartridge battery. However, the pictures dont work any more and the guide has a giant error in it. This is dethbydeseption's guide, I only updated it. Thanks dethbydeseption for such an awesome guide! You're a wily dude.
WARNING
If you don't follow this guide to the letter you risk completely ruining your game. However, if you work slowly and use the same tools as I did, you'll do just fine. I also need to make it clear that you'll lose ALL your data the moment you remove the original battery. Make sure to transfer your Pokemon and items beforehand. If you make an accident and ruin your game, I'm so very sorry. This method DOES work so long as you're gentle with your circuit board. If you're a little on the clumsy side or you're too young, get an adult to free the battery for you.
Supplies
Ok so you won't need much to replace your battery. Here's a picture with the supplies you'll need and a ruler to give you a sense of scale for the pliers.
i11.photobucket.com/albums/a151/Uriel3ca/Pokemon%20battery%20guide/required.jpg
You -must- have:
* Electrical tape (secure the battery)
* A hobby knife (you need this to pry the brackets away from the battery)
* A CR2032 (or similar, I suppose) 3 volt battery (i11.photobucket.com/albums/a151/Uriel3ca/Pokemon%20battery%20guide/pokemon001.jpg)
* A TINY pair of pliers to grasp the little screw that holds the game together (I tried EVERYTHING else. Trust me, jeweler's pliers are the only things aside from the crazy-looking specialized screwdriver Nintendo used that'll budge the screw)
All of these supplies can be picked up at your local craft and hardware stores- not to mention Radio Shack for the battery. Be prepared to spend a total of 10-20$ for these required supplies.
The Process
Ok, so first, you need to find a well-lit, hard wood place to work at. A kitchen table or living-room floor maybe? Carpets probably won't ruin your game but.. you can't be too careful. Now take your tiny pliers and do your best to grasp the screw in the back of your cartridge. It's a bit tricky, but keep at it. You really can't ruin your game by being rough with the cartridge itself but just be careful not to strip the little screw's head bare. You may need to change the battery in another ten years? ;P
i11.photobucket.com/albums/a151/Uriel3ca/Pokemon%20battery%20guide/pokemon002.jpg
The lid is off! Simple. The battery is in plain sight and this leads us to the very gentle part.
i11.photobucket.com/albums/a151/Uriel3ca/Pokemon%20battery%20guide/pokemon004.jpg
You must CAREFULLY dig under the little metal foot on the battery and start sawing through the one (or sometimes two) little rivet-looking things that are holding the battery in place. I would wedge the blade in and give a little twist to pry the foot up ever so before I began sawing. This is where you must take little steps and GO SLOWLY! If your knife accidentally slips out of control and tags a chip or the board itself (A little cut on the green part wont ruin it but stay FAR away from the chips and various golden circuits) your game will be broken. The metal foot will probably get horribly bent but
DO NOT SNAP IT OFF!
If you do, there'll be no way to attach your battery. It took me roughly 7 minutes to saw and twist my way through the top and bottom. i11.photobucket.com/albums/a151/Uriel3ca/Pokemon%20battery%20guide/pokemon010.jpg
Though the whole procedure is tricky, the bottom is VERY DANGEROUS! The same danger is present but its even worse now. There's no battery between your knife and the board itself.
i11.photobucket.com/albums/a151/Uriel3ca/Pokemon%20battery%20guide/pokemon010.jpg
The temptation to wrench the battery out is very great indeed but DON'T! Hold the battery firmly so you don't accidentally rip the foot off the circuit board. Remember how we freed the top: slip the blade down, twist, saw, twist, saw. Don't be afraid to pull the bottom-most, last little rivet out after you saw it for a minute or two. It comes free pretty easy after you weaken it with the hobby blade.