Without your AC charger / adapter, you can feel just like your laptop is next to meaningless. Of course, not only do you not have a method to charge the battery in your laptop, you do not have a method to run your computer through a wall outlet. While new technologies are being developed each day in the area of mobile power solutions (including Intel's research into wireless electric transmissions), there aren't a lot of current alternative choices to charging your laptop battery without a charger. If your problem is you're without your original charger (which is what typically has a new laptop), these are some workarounds you can try that may keep your laptop humming. Bear in mind, though, that they cost cash and require a complicated purchase, in which particular case it could be just as cost-effective and suitable to purchase a new charger from your laptop's manufacturer.
Utilize a universal power adapter. This is maybe the most blatant answer to your battery problems. Quickly found at most stores that carry electronics, a universal power adapter can range anywhere in price from $30 to $100 (or even more, dependent on how fancy you get). The adapter includes multiple tips, one of which should likely fit your laptop's charging port. When plugged in, the adapter won't only power your laptop, but will charge its battery also.
Utilize a universal automobile / air adapter. If you are the road-warrior type who allocates more time in your auto than at a desk, this could be the sensible solution for you. A vehicle adapter is comparable to a regular power adapter, except it's got an altered end that plugs into your car's fag lighter. The adapter will keep you powered while in your vehicle (or in-flight if it is a combo adapter), and will concurrently charge your laptop so you are prepared for those occasions when you have to leave your vehicle or plane for real life.
Buy an external laptop battery charger. These are stand-alone devices that don't plug into your laptop. Rather, you take the battery out of your laptop, attach it to the charger, plug the charger into an electric outlet, and rejoice your battery that way. When entirely charged, you reinsert the battery into your laptop. External chargers are often brand and model categorical, so be sure you get one that matches your laptop's specs. One advantage to an external battery charger is you can charge spare batteries without tying up your laptop.