Aerobeds are large, and it can be difficult to locate the sources of a leak right away. Until you know where the leak is, you can't patch it and restore it to its former, comfortable self. Finding the leak takes detective work and a bit of luck.
Go over every inch of the inflated Aerobed with your naked eye, looking for puncture marks. If you see one, circle it with your pen so that you don't lose it if you look away.
Have someone rest on the Aerobed and listen for a high-pitched, soft whining sound. The air escaping the mattress may make a noise, and if you locate the noise, you've located the leak.
Run your hands over the Aerobed, seeking ruptures in its otherwise smooth surface. Your hands may feel a small imperfection that your eyes won't notice at first. Mark anything you find.
Mix dishwashing soap and water together in a spray bottle and spray it on different areas of the inflated Aerobed. If there's a leak, the mixture should bubble when it finds it.
Examine the seams with a magnifying glass. Leaks and tears there tend to escape the naked eye.
Remove the gasket valve cover. Soak it in warm water for 10 minute, then let it dry. Fit it back onto the Aerobed and reinflate it. If it holds without leaking, then the leak was around the gasket seal.