I have a pretty new Toshiba satellite laptop and it used to work fine, but now I'm have battery problems. The laptop recognizes that there is a battery, but it every time I unplug the charger, the laptop immediately shuts off. It also won't charge past 76% and says plugged in, not charging. Every few days the percent lowers. Any suggestions?
Most modern laptop will only charge the battery to around 60% - 80% depending on what the manufacturer decides to set it to. That is done to extend the battery life. Without going into too many details. The more often the battery is at full charge, the sooner the battery life will become shorter. It's like the more you use it, the sooner it will need to be replaced. Keeping the battery below a full charge can extend the battery life. The manual should tell you how to override so that the battery charges to 100% if you are going use it away from an A/C outlet.
Since the laptop shuts down when you unplug the charger, then you definitely have a problem. It could be the battery, or it could be the laptop itself. You likely need to get it serviced under warranty.
Some models of the Toshiba Satellites have a problem with the motherboard that causes the battery to not charge without the power cord. This requires them to be shipped back to the factory for repair. It's covered under warranty as long as this problem is observed during the warranty period. Just contact Toshiba and they will give instructions.