The internal battery in your game cartridge has died.
If you use an emulator and a ROM, then click on this link and you may find the answer: http://www.vbalink.info/internal-battery-has-run-dry-fix.htm However, if you use an actual game cartridge, then you will have to disassemble the cartridge (unscrew the screw on the back) and then replace the battery.
The internal battery has probably ran dry. To fix this, open your cartridge and replace the battery.
Most likely because the internal battery in your game is dead. It won't save unless you replace the battery inside of the game's cartridge.
One possible problem could be wear and tear on the internals of the game cartridge. This is more likely if the game was bought used or if the game used to save properly but now does not. If the game never saved properly and was not bought from a reputable seller, it is possible that it is a fake copy of the game. A few telltale signs are the cartridge itself not being red and slightly transparent or the label being crooked or not shiny. Despite common beliefs, this is not an issue with the battery. With Pokemon Ruby, the internal battery of the cartridge only controls the internal clock. While clock-based events, such as berries growing, will not function if the battery is not working, saving is completely unaffected.
Yes, it's sometimes possible to revive the battery in this way, doesn't have to use a Gamecube either, just leaving the cartridge in a GBA while it charges from the mains charger should do. But the fix is not certain, and you might have to replace the battery.
The saved data on a GBA cartridge is maintained by a small battery. If this battery goes flat, the data will be lost. If your GBA cartridge is unable to save, you will need to open the cartridge up and replace the battery.
If your Pokemon game keeps restarting and is unable to save it means that the internal battery in the cartridge is dead. You can either replace the battery or buy a new game. If your interested in replacing the battery you need a CR2025 coin cell battery. They're about 5 bucks
The Internal Battery has most likely died. This Can Happen to any cartridge over a long period of time.
sometimes
No way possible...
if it is saying "save file corrupted" then your internal battery is dead. this battery powers the chip that saves data. to fix this just Google "how to replace a GBC internal battery". This same thing happened to me with my Pokemon crystal but i fixed it in a half an hour for less than $10.